diff --git a/pom.xml b/pom.xml
index 0bf868886f..25b95a9368 100644
--- a/pom.xml
+++ b/pom.xml
@@ -92,6 +92,7 @@
                     <groupId>org.apache.maven.plugins</groupId>
                     <artifactId>maven-surefire-plugin</artifactId>
                     <configuration>
+                        <argLine>-Duser.language=en -Duser.region=US</argLine>
                         <classpathDependencyExcludes>
                             <classpathDependencyExclude>com.powsybl:powsybl-config-classic</classpathDependencyExclude>
                         </classpathDependencyExcludes>
diff --git a/src/main/java/com/powsybl/openloadflow/ac/outerloop/ReactiveLimitsOuterLoop.java b/src/main/java/com/powsybl/openloadflow/ac/outerloop/ReactiveLimitsOuterLoop.java
index 07fb06c47d..f068c0d82d 100644
--- a/src/main/java/com/powsybl/openloadflow/ac/outerloop/ReactiveLimitsOuterLoop.java
+++ b/src/main/java/com/powsybl/openloadflow/ac/outerloop/ReactiveLimitsOuterLoop.java
@@ -187,7 +187,7 @@ private static boolean switchPqPv(List<PqToPvBus> pqToPvBuses, ContextData conte
 
             int pvPqSwitchCount = contextData.getPvPqSwitchCount(controllerBus.getId());
             if (pvPqSwitchCount >= maxPqPvSwitch) {
-                pqPvNodes.add(Reports.reportPvPqSwitchLimit(reportNode, controllerBus, pvPqSwitchCount, log, LOGGER));
+                pqPvNodes.add(Reports.createRootReportPvPqSwitchLimit(reportNode, controllerBus, pvPqSwitchCount, log, LOGGER));
             } else {
                 controllerBus.setGeneratorVoltageControlEnabled(true);
                 controllerBus.setGenerationTargetQ(0);
@@ -195,7 +195,7 @@ private static boolean switchPqPv(List<PqToPvBus> pqToPvBuses, ContextData conte
                 pqPvSwitchCount++;
 
                 if (pqToPvBus.limitType.isMaxLimit()) {
-                    pqPvNodes.add(Reports.reportPqToPvBusMaxLimit(
+                    pqPvNodes.add(Reports.createRootReportPqToPvBusMaxLimit(
                             reportNode,
                             controllerBus,
                             controllerBus.getGeneratorVoltageControl().map(VoltageControl::getControlledBus).orElseThrow(),
@@ -203,7 +203,7 @@ private static boolean switchPqPv(List<PqToPvBus> pqToPvBuses, ContextData conte
                             log,
                             LOGGER));
                 } else {
-                    pqPvNodes.add(Reports.reportPqToPvBusMinLimit(
+                    pqPvNodes.add(Reports.createRootReportPqToPvBusMinLimit(
                             reportNode,
                             controllerBus,
                             controllerBus.getGeneratorVoltageControl().map(VoltageControl::getControlledBus).orElseThrow(),
@@ -345,10 +345,10 @@ private boolean switchReactiveControllerBusPq(List<ControllerBusToPqBus> reactiv
 
             switch (bus.limitType) {
                 case MAX_Q:
-                    switchedNodes.add(Reports.reportReactiveControllerBusesToPqMaxQ(reportNode, controllerBus, bus.q, bus.qLimit, log, LOGGER));
+                    switchedNodes.add(Reports.createRootReportReactiveControllerBusesToPqMaxQ(reportNode, controllerBus, bus.q, bus.qLimit, log, LOGGER));
                     break;
                 case MIN_Q:
-                    switchedNodes.add(Reports.reportReactiveControllerBusesToPqMinQ(reportNode, controllerBus, bus.q, bus.qLimit, log, LOGGER));
+                    switchedNodes.add(Reports.createRootReportReactiveControllerBusesToPqMinQ(reportNode, controllerBus, bus.q, bus.qLimit, log, LOGGER));
                     break;
                 case MIN_REALISTIC_V, MAX_REALISTIC_V:
                     // Note: never happens for now. Robust mode applies only to remote voltage control generators
diff --git a/src/main/java/com/powsybl/openloadflow/sa/AbstractSecurityAnalysis.java b/src/main/java/com/powsybl/openloadflow/sa/AbstractSecurityAnalysis.java
index dc0855bccd..ce65d41f80 100644
--- a/src/main/java/com/powsybl/openloadflow/sa/AbstractSecurityAnalysis.java
+++ b/src/main/java/com/powsybl/openloadflow/sa/AbstractSecurityAnalysis.java
@@ -220,7 +220,7 @@ SecurityAnalysisReport runSync(SecurityAnalysisParameters securityAnalysisParame
 
                             parameters = createParameters(lfParameters, lfParametersExt, partitionTopoConfig.isBreaker(), isAreaInterchangeControl(lfParametersExt, contingencies));
 
-                            ReportNode threadRootNode = partitionNum == 0 ? saReportNode : Reports.createThreadRootReport(saReportNode);
+                            ReportNode threadRootNode = partitionNum == 0 ? saReportNode : Reports.createRootThreadReport(saReportNode);
                             reportNodes.set(partitionNum, threadRootNode);
 
                             // create networks including all necessary switches
diff --git a/src/main/java/com/powsybl/openloadflow/util/Reports.java b/src/main/java/com/powsybl/openloadflow/util/Reports.java
index f895773c9d..9dd450fd3b 100644
--- a/src/main/java/com/powsybl/openloadflow/util/Reports.java
+++ b/src/main/java/com/powsybl/openloadflow/util/Reports.java
@@ -309,7 +309,7 @@ public static ReportNode reportPqToPvBuses(ReportNode reportNode, int pqToPvBusC
                 .add();
     }
 
-    public static ReportNode reportPvPqSwitchLimit(ReportNode firstRootReportNode, LfBus controllerBus, int limit, boolean log, Logger logger) {
+    public static ReportNode createRootReportPvPqSwitchLimit(ReportNode firstRootReportNode, LfBus controllerBus, int limit, boolean log, Logger logger) {
         ReportNode result = ReportNode.newRootReportNode()
                 .withLocale(firstRootReportNode.getTreeContext().getLocale())
                 .withResourceBundles(PowsyblOpenLoadFlowReportResourceBundle.BASE_NAME)
@@ -324,7 +324,7 @@ public static ReportNode reportPvPqSwitchLimit(ReportNode firstRootReportNode, L
         return result;
     }
 
-    public static ReportNode reportPqToPvBusMaxLimit(ReportNode firstRootReportNode, LfBus controllerBus, LfBus controlledBus, double targetV, boolean log, Logger logger) {
+    public static ReportNode createRootReportPqToPvBusMaxLimit(ReportNode firstRootReportNode, LfBus controllerBus, LfBus controlledBus, double targetV, boolean log, Logger logger) {
         ReportNode result = ReportNode.newRootReportNode()
                 .withLocale(firstRootReportNode.getTreeContext().getLocale())
                 .withResourceBundles(PowsyblOpenLoadFlowReportResourceBundle.BASE_NAME)
@@ -342,7 +342,7 @@ public static ReportNode reportPqToPvBusMaxLimit(ReportNode firstRootReportNode,
         return result;
     }
 
-    public static ReportNode reportPqToPvBusMinLimit(ReportNode firstRootReportNode, LfBus controllerBus, LfBus controlledBus, double targetV, boolean log, Logger logger) {
+    public static ReportNode createRootReportPqToPvBusMinLimit(ReportNode firstRootReportNode, LfBus controllerBus, LfBus controlledBus, double targetV, boolean log, Logger logger) {
         ReportNode result = ReportNode.newRootReportNode()
                 .withLocale(firstRootReportNode.getTreeContext().getLocale())
                 .withResourceBundles(PowsyblOpenLoadFlowReportResourceBundle.BASE_NAME)
@@ -384,12 +384,12 @@ public static ReportNode reportReactiveControllerBusesToPqBuses(ReportNode repor
                 .add();
     }
 
-    public static ReportNode reportReactiveControllerBusesToPqMaxQ(ReportNode firstRootReportNode,
-                                                                   LfBus controllerBus,
-                                                                   double busQ,
-                                                                   double maxQ,
-                                                                   boolean log,
-                                                                   Logger logger) {
+    public static ReportNode createRootReportReactiveControllerBusesToPqMaxQ(ReportNode firstRootReportNode,
+                                                                             LfBus controllerBus,
+                                                                             double busQ,
+                                                                             double maxQ,
+                                                                             boolean log,
+                                                                             Logger logger) {
         ReportNode result = ReportNode.newRootReportNode()
                 .withLocale(firstRootReportNode.getTreeContext().getLocale())
                 .withResourceBundles(PowsyblOpenLoadFlowReportResourceBundle.BASE_NAME)
@@ -405,12 +405,12 @@ public static ReportNode reportReactiveControllerBusesToPqMaxQ(ReportNode firstR
         return result;
     }
 
-    public static ReportNode reportReactiveControllerBusesToPqMinQ(ReportNode firstRootReportNode,
-                                                                   LfBus controllerBus,
-                                                                   double busQ,
-                                                                   double minQ,
-                                                                   boolean log,
-                                                                   Logger logger) {
+    public static ReportNode createRootReportReactiveControllerBusesToPqMinQ(ReportNode firstRootReportNode,
+                                                                             LfBus controllerBus,
+                                                                             double busQ,
+                                                                             double minQ,
+                                                                             boolean log,
+                                                                             Logger logger) {
         ReportNode result = ReportNode.newRootReportNode()
                 .withLocale(firstRootReportNode.getTreeContext().getLocale())
                 .withResourceBundles(PowsyblOpenLoadFlowReportResourceBundle.BASE_NAME)
@@ -895,7 +895,7 @@ public static void reportActionApplicationFailure(String actionId, String contin
                 .add();
     }
 
-    public static ReportNode createThreadRootReport(ReportNode firstRootReport) {
+    public static ReportNode createRootThreadReport(ReportNode firstRootReport) {
         return ReportNode.newRootReportNode()
                 .withLocale(firstRootReport.getTreeContext().getLocale())
                 .withAllResourceBundlesFromClasspath()
diff --git a/src/test/java/com/powsybl/openloadflow/ac/DistributedSlackOnGenerationTest.java b/src/test/java/com/powsybl/openloadflow/ac/DistributedSlackOnGenerationTest.java
index cdc4f7da7a..99cbcfd78e 100644
--- a/src/test/java/com/powsybl/openloadflow/ac/DistributedSlackOnGenerationTest.java
+++ b/src/test/java/com/powsybl/openloadflow/ac/DistributedSlackOnGenerationTest.java
@@ -35,10 +35,7 @@
 import org.junit.jupiter.api.BeforeEach;
 import org.junit.jupiter.api.Test;
 
-import java.util.EnumSet;
-import java.util.List;
-import java.util.OptionalDouble;
-import java.util.Set;
+import java.util.*;
 import java.util.concurrent.CompletionException;
 
 import static com.powsybl.openloadflow.util.LoadFlowAssert.*;
diff --git a/src/test/java/com/powsybl/openloadflow/sa/OpenSecurityAnalysisWithActionsTest.java b/src/test/java/com/powsybl/openloadflow/sa/OpenSecurityAnalysisWithActionsTest.java
index c703786216..9ed28ff74d 100644
--- a/src/test/java/com/powsybl/openloadflow/sa/OpenSecurityAnalysisWithActionsTest.java
+++ b/src/test/java/com/powsybl/openloadflow/sa/OpenSecurityAnalysisWithActionsTest.java
@@ -43,10 +43,7 @@
 
 import java.io.ByteArrayInputStream;
 import java.io.IOException;
-import java.util.ArrayList;
-import java.util.Collections;
-import java.util.List;
-import java.util.Set;
+import java.util.*;
 import java.util.concurrent.CompletionException;
 import java.util.stream.Stream;
 
diff --git a/src/test/resources/i18n/reports_en.properties b/src/test/resources/i18n/reports_en.properties
deleted file mode 100644
index 8b13789179..0000000000
--- a/src/test/resources/i18n/reports_en.properties
+++ /dev/null
@@ -1 +0,0 @@
-