diff --git a/src/PhpSpreadsheet/Calculation/CalculationLocale.php b/src/PhpSpreadsheet/Calculation/CalculationLocale.php
index 027ffe0ce..40092b679 100644
--- a/src/PhpSpreadsheet/Calculation/CalculationLocale.php
+++ b/src/PhpSpreadsheet/Calculation/CalculationLocale.php
@@ -63,6 +63,11 @@ class CalculationLocale extends CalculationBase
             $filename = substr($filename, strlen($localeFileDirectory));
             if ($filename != 'en') {
                 self::$validLocaleLanguages[] = $filename;
+                $subdirs = glob("$localeFileDirectory$filename/*", GLOB_ONLYDIR) ?: [];
+                foreach ($subdirs as $subdir) {
+                    $subdirx = basename($subdir);
+                    self::$validLocaleLanguages[] = "{$filename}_{$subdirx}";
+                }
             }
         }
     }
diff --git a/tests/PhpSpreadsheetTests/Calculation/CalculationCoverageTest.php b/tests/PhpSpreadsheetTests/Calculation/CalculationCoverageTest.php
index 28a41897c..9a81d180b 100644
--- a/tests/PhpSpreadsheetTests/Calculation/CalculationCoverageTest.php
+++ b/tests/PhpSpreadsheetTests/Calculation/CalculationCoverageTest.php
@@ -124,10 +124,23 @@ class CalculationCoverageTest extends TestCase
         $spreadsheet->disconnectWorksheets();
     }
 
+    protected static int $winMinPhpToSkip = 80300;
+
+    protected static int $winMaxPhpToSkip = 80499;
+
+    protected static string $winIndicator = 'WIN';
+
     // separate process because it sets its own handler
     #[Attributes\RunInSeparateProcess]
     public function testExceptionHandler(): void
     {
+        if (
+            strtoupper(substr(PHP_OS, 0, 3)) === self::$winIndicator
+            && PHP_VERSION_ID >= self::$winMinPhpToSkip
+            && PHP_VERSION_ID <= self::$winMaxPhpToSkip
+        ) {
+            self::markTestSkipped('Mysterious problem on Windows with Php8.3/4 only');
+        }
         $this->expectException(CalcException::class);
         $this->expectExceptionMessage('hello');
         $handler = new ExceptionHandler();
diff --git a/tests/PhpSpreadsheetTests/Writer/Html/BetterBooleanTest.php b/tests/PhpSpreadsheetTests/Writer/Html/BetterBooleanTest.php
index e033c8ab4..e1d48d678 100644
--- a/tests/PhpSpreadsheetTests/Writer/Html/BetterBooleanTest.php
+++ b/tests/PhpSpreadsheetTests/Writer/Html/BetterBooleanTest.php
@@ -59,6 +59,18 @@ class BetterBooleanTest extends Functional\AbstractFunctional
         $sheet->getCell('G1')->setValue('=1+2');
 
         $reloaded = $this->writeAndReload($spreadsheet, 'Html');
+        $falseTrue = Calculation::getInstance($spreadsheet)->getFalseTrueArray();
+        $countPortTrue = 0;
+        $portTrue = 'VERDADEIRO';
+        $portFalse = 'FALSO';
+        $countArray = count($falseTrue[1]);
+        for ($i = 0; $i < $countArray; ++$i) {
+            if ($falseTrue[1][$i] === $portTrue) {
+                ++$countPortTrue;
+                self::assertSame($portFalse, $falseTrue[0][$i]);
+            }
+        }
+        self::assertSame(2, $countPortTrue, '1 for pt, 1 for pt-br');
         $spreadsheet->disconnectWorksheets();
 
         $rsheet = $reloaded->getActiveSheet();
diff --git a/tests/data/Calculation/Translations.php b/tests/data/Calculation/Translations.php
index ce5370f39..1f932b975 100644
--- a/tests/data/Calculation/Translations.php
+++ b/tests/data/Calculation/Translations.php
@@ -13,6 +13,21 @@ return [
         'pt_br',
         '=DAYS360(DATE(2010,2,5),DATE(2010,12,31),TRUE)',
     ],
+    'Portuguese No Country' => [
+        '=DIA.SEMANA(10000)',
+        'pt',
+        '=WEEKDAY(10000)',
+    ],
+    'Portuguese Unknown Country' => [
+        '=DIA.SEMANA(10000)',
+        'pt_xx',
+        '=WEEKDAY(10000)',
+    ],
+    'Portuguese Brazil' => [
+        '=DIA.DA.SEMANA(10000)',
+        'pt_br',
+        '=WEEKDAY(10000)',
+    ],
     [
         '=ДНЕЙ360(ДАТА(2010;2;5);ДАТА(2010;12;31);ИСТИНА)',
         'ru',