diff --git a/packages/xl-docx-exporter/src/docx/__snapshots__/basic/styles.xml b/packages/xl-docx-exporter/src/docx/__snapshots__/basic/styles.xml
index d23b5bb2ff..fa0a655a69 100644
--- a/packages/xl-docx-exporter/src/docx/__snapshots__/basic/styles.xml
+++ b/packages/xl-docx-exporter/src/docx/__snapshots__/basic/styles.xml
@@ -7,7 +7,7 @@
                 <w:kern w:val="2"/>
                 <w:sz w:val="24"/>
                 <w:szCs w:val="24"/>
-                <w:lang w:val="en-NL" w:eastAsia="en-GB" w:bidi="ar-SA"/>
+                <w:lang w:val="en-US" w:eastAsia="en-GB" w:bidi="ar-SA"/>
                 <w14:ligatures w14:val="standardContextual"/>
             </w:rPr>
         </w:rPrDefault>
diff --git a/packages/xl-docx-exporter/src/docx/__snapshots__/withMultiColumn/styles.xml b/packages/xl-docx-exporter/src/docx/__snapshots__/withMultiColumn/styles.xml
index d23b5bb2ff..fa0a655a69 100644
--- a/packages/xl-docx-exporter/src/docx/__snapshots__/withMultiColumn/styles.xml
+++ b/packages/xl-docx-exporter/src/docx/__snapshots__/withMultiColumn/styles.xml
@@ -7,7 +7,7 @@
                 <w:kern w:val="2"/>
                 <w:sz w:val="24"/>
                 <w:szCs w:val="24"/>
-                <w:lang w:val="en-NL" w:eastAsia="en-GB" w:bidi="ar-SA"/>
+                <w:lang w:val="en-US" w:eastAsia="en-GB" w:bidi="ar-SA"/>
                 <w14:ligatures w14:val="standardContextual"/>
             </w:rPr>
         </w:rPrDefault>
diff --git a/packages/xl-docx-exporter/src/docx/docxExporter.test.ts b/packages/xl-docx-exporter/src/docx/docxExporter.test.ts
index d9d3adeb2b..a7bf9edbb4 100644
--- a/packages/xl-docx-exporter/src/docx/docxExporter.test.ts
+++ b/packages/xl-docx-exporter/src/docx/docxExporter.test.ts
@@ -28,7 +28,11 @@ describe("exporter", () => {
       }),
       docxDefaultSchemaMappings,
     );
-    const doc = await exporter.toDocxJsDocument(testDocument);
+    const doc = await exporter.toDocxJsDocument(testDocument, {
+      sectionOptions: {},
+      documentOptions: {},
+      locale: "en-US",
+    });
 
     const blob = await Packer.toBlob(doc);
     const zip = new ZipReader(new BlobReader(blob));
@@ -56,6 +60,7 @@ describe("exporter", () => {
       );
 
       const doc = await exporter.toDocxJsDocument(testDocument, {
+        locale: "en-US",
         documentOptions: {
           creator: "John Doe",
         },
@@ -181,6 +186,7 @@ describe("exporter", () => {
             ],
           },
         ]),
+        { sectionOptions: {}, documentOptions: {}, locale: "en-US" },
       );
 
       const blob = await Packer.toBlob(doc);
diff --git a/packages/xl-docx-exporter/src/docx/docxExporter.ts b/packages/xl-docx-exporter/src/docx/docxExporter.ts
index 9e2ddfd6b6..6a79d5c53d 100644
--- a/packages/xl-docx-exporter/src/docx/docxExporter.ts
+++ b/packages/xl-docx-exporter/src/docx/docxExporter.ts
@@ -187,10 +187,21 @@ export class DOCXExporter<
     ];
   }
 
-  protected async createDefaultDocumentOptions(): Promise<DocumentOptions> {
-    const externalStyles = (await import("./template/word/styles.xml?raw"))
+  protected async createDefaultDocumentOptions(
+    locale?: string,
+  ): Promise<DocumentOptions> {
+    let externalStyles = (await import("./template/word/styles.xml?raw"))
       .default;
 
+    // Replace the default language in styles.xml with the provided locale.
+    // If not provided, default to en-US.
+    const resolvedLocale = (locale && locale.trim()) || "en-US";
+
+    externalStyles = externalStyles.replace(
+      /(<w:lang\b[^>]*\bw:val=")([^"]+)("[^>]*\/>)/g,
+      `$1${resolvedLocale}$3`,
+    );
+
     const bullets = ["•"]; //, "◦", "▪"]; (these don't look great, just use solid bullet for now)
     return {
       numbering: {
@@ -247,6 +258,11 @@ export class DOCXExporter<
     options: {
       sectionOptions: Omit<ISectionOptions, "children">;
       documentOptions: DocumentOptions;
+      /**
+       * The document locale in OOXML format (e.g. en-US, fr-FR, de-DE).
+       * If omitted, defaults to en-US.
+       */
+      locale?: string;
     } = {
       sectionOptions: {},
       documentOptions: {},
@@ -276,13 +292,18 @@ export class DOCXExporter<
     options: {
       sectionOptions: Omit<ISectionOptions, "children">;
       documentOptions: DocumentOptions;
+      /**
+       * The document locale in OOXML format (e.g. en-US, fr-FR, de-DE).
+       * If omitted, defaults to en-US.
+       */
+      locale?: string;
     } = {
       sectionOptions: {},
       documentOptions: {},
     },
   ) {
     const doc = new Document({
-      ...(await this.createDefaultDocumentOptions()),
+      ...(await this.createDefaultDocumentOptions(options.locale)),
       ...options.documentOptions,
       sections: [
         {
diff --git a/shared/util/fileUtil.ts b/shared/util/fileUtil.ts
index 0a8c3d8ed4..6f77bf3a7a 100644
--- a/shared/util/fileUtil.ts
+++ b/shared/util/fileUtil.ts
@@ -36,6 +36,12 @@ export async function loadFileBuffer(requireUrl: {
     if (url.startsWith("/@fs/")) {
       url = url.substring("/@fs".length);
     }
+    // On Windows, vite/vitest may yield paths like "/C:/..." after removing /@fs
+    // Node on Windows treats paths starting with "/" as relative to current drive,
+    // which would produce "C:\C:\...". Strip leading slash when followed by a drive letter.
+    if (/^\/[A-Za-z]:/.test(url)) {
+      url = url.slice(1);
+    }
     const buffer = fs.readFileSync(url);
     return buffer;
   } else {