diff --git a/components/desktop/desktop-host.tsx b/components/desktop/desktop-host.tsx
index f8295a3ad..29aa70dd6 100644
--- a/components/desktop/desktop-host.tsx
+++ b/components/desktop/desktop-host.tsx
@@ -118,7 +118,7 @@ export function DesktopHost() {
   // Menus and spellcheck follow the interface.
   useEffect(() => {
     const ui = uiLocale || document.documentElement.lang;
-    if (ui) setDesktopInterfaceLanguage(ui, shellLabels(tRef.current as unknown as (key: string) => string));
+    if (ui) setDesktopInterfaceLanguage(ui, shellLabels(tRef.current as unknown as Parameters<typeof shellLabels>[0]));
   }, [uiLocale]);
 
   // What the user writes in, whichever composer asks for it too.
diff --git a/lib/desktop/__tests__/shell-labels.test.ts b/lib/desktop/__tests__/shell-labels.test.ts
new file mode 100644
index 000000000..563c194d4
--- /dev/null
+++ b/lib/desktop/__tests__/shell-labels.test.ts
@@ -0,0 +1,45 @@
+import { readdirSync, readFileSync } from 'node:fs';
+import { join } from 'node:path';
+import { describe, expect, it } from 'vitest';
+import { createTranslator } from 'use-intl/core';
+import { shellLabels } from '../languages';
+
+/**
+ * The real catalogs through the real formatter, which the vitest next-intl mock isn't.
+ * A string that needs a value and doesn't get one is an error here. In the app it's a
+ * logged error, and the desktop's menu would show the key instead of the label.
+ */
+const LOCALES_DIR = join(process.cwd(), 'locales');
+const LOCALES = readdirSync(LOCALES_DIR, { withFileTypes: true }).filter((entry) => entry.isDirectory()).map((entry) => entry.name);
+
+function labelsFor(locale: string): { labels: Record<string, string>; errors: string[] } {
+  const messages = JSON.parse(readFileSync(join(LOCALES_DIR, locale, 'common.json'), 'utf8'));
+  const errors: string[] = [];
+  const t = createTranslator({
+    locale,
+    messages,
+    onError: (error) => { errors.push(`${locale}: ${error.message.slice(0, 160)}`); },
+  });
+  return { labels: shellLabels(t as unknown as Parameters<typeof shellLabels>[0]), errors };
+}
+
+describe('the labels the desktop shell gets', () => {
+  it('finds every language', () => {
+    expect(LOCALES.length).toBeGreaterThanOrEqual(30);
+  });
+
+  it.each(LOCALES)('%s: every string formats, with no value missing', (locale) => {
+    const { labels, errors } = labelsFor(locale);
+    expect(errors).toEqual([]);
+    for (const [name, label] of Object.entries(labels)) {
+      expect(label, name).not.toMatch(/^[\w-]+(\.[\w-]+)+$/);
+      expect(label.trim(), name).not.toBe('');
+    }
+  });
+
+  it.each(LOCALES)('%s: leaves the shell its placeholders to fill in', (locale) => {
+    const { labels } = labelsFor(locale);
+    expect(labels.contextAddToDictionary).toContain('{word}');
+    expect(labels.unsentMany).toContain('{count}');
+  });
+});
diff --git a/lib/desktop/languages.ts b/lib/desktop/languages.ts
index 5c054dc28..f8c4da69b 100644
--- a/lib/desktop/languages.ts
+++ b/lib/desktop/languages.ts
@@ -33,8 +33,12 @@ export function noteComposerLanguage(key: string, language: string | null): void
   push();
 }
 
-/** The shell's text in the interface language, by its keys in src/main/strings.ts. */
-export function shellLabels(t: (key: string) => string): Record<string, string> {
+/**
+ * The shell's text in the interface language, by its keys in src/main/strings.ts. The
+ * shell fills in `{word}` and `{count}` itself when it shows them, so they go over as
+ * they are. Without a value next-intl gives back the key, and that would be the label.
+ */
+export function shellLabels(t: (key: string, values?: Record<string, string>) => string): Record<string, string> {
   return {
     menuFile: t('desktopUi.menu.file'),
     menuEdit: t('desktopUi.menu.edit'),
@@ -99,7 +103,7 @@ export function shellLabels(t: (key: string) => string): Record<string, string>
     contextCopy: t('desktopUi.menu.copy'),
     contextPaste: t('desktopUi.menu.paste'),
     contextSelectAll: t('desktopUi.menu.select_all'),
-    contextAddToDictionary: t('desktopUi.context.add_to_dictionary'),
+    contextAddToDictionary: t('desktopUi.context.add_to_dictionary', { word: '{word}' }),
     contextNoSuggestions: t('desktopUi.context.no_suggestions'),
     contextOpenLink: t('desktopUi.context.open_link'),
     contextCopyLink: t('desktopUi.context.copy_link'),
@@ -111,7 +115,7 @@ export function shellLabels(t: (key: string) => string): Record<string, string>
     closeAnyway: t('desktopUi.closing.close_anyway'),
     unsentTitle: t('desktopUi.closing.unsent_title'),
     unsentOne: t('desktopUi.closing.unsent_one'),
-    unsentMany: t('desktopUi.closing.unsent_many'),
+    unsentMany: t('desktopUi.closing.unsent_many', { count: '{count}' }),
     closeNow: t('desktopUi.closing.quit'),
     leaveTitle: t('desktopUi.closing.leave_title'),
     leaveDetail: t('desktopUi.closing.leave_detail'),