diff --git a/src/extension/_locales/ko-kr/messages.json b/src/extension/_locales/ko/messages.json
similarity index 100%
rename from src/extension/_locales/ko-kr/messages.json
rename to src/extension/_locales/ko/messages.json
diff --git a/src/extension/_locales/pt-br/messages.json b/src/extension/_locales/pt_BR/messages.json
similarity index 100%
rename from src/extension/_locales/pt-br/messages.json
rename to src/extension/_locales/pt_BR/messages.json
diff --git a/src/extension/_locales/zh-cn/messages.json b/src/extension/_locales/zh_CN/messages.json
similarity index 100%
rename from src/extension/_locales/zh-cn/messages.json
rename to src/extension/_locales/zh_CN/messages.json
diff --git a/src/extension/_locales/zh-tw/messages.json b/src/extension/_locales/zh_TW/messages.json
similarity index 100%
rename from src/extension/_locales/zh-tw/messages.json
rename to src/extension/_locales/zh_TW/messages.json
diff --git a/src/extension/background.js b/src/extension/background.js
index 20b2c1045..b8dc3f52f 100644
--- a/src/extension/background.js
+++ b/src/extension/background.js
@@ -28,7 +28,6 @@ import {
   getGitHubSettings,
   setConfig,
   getConfig,
-  updateProjectConfigs,
   populateUrlCache,
   queryUrlCache,
   setDisplay,
@@ -46,10 +45,10 @@ const LANGS = [
   'fr',
   'it',
   'ja',
-  'ko-kr',
-  'pt-br',
-  'zh-cn',
-  'zh-tw',
+  'ko',
+  'pt_BR',
+  'zh_CN',
+  'zh_TW',
 ];
 
 /**
@@ -321,15 +320,16 @@ function toggle(id) {
 }
 
 /**
- * Retrieves the sidekick language preferred by the user.
+ * Retrieves the help language based on the language preferred by the user.
  * The default language is <code>en</code>.
  * @private
  * @return {string} The language
  */
-function getLanguage() {
-  return navigator.languages
-    .map((prefLang) => LANGS.find((lang) => prefLang.toLowerCase().startsWith(lang)))
-    .filter((lang) => !!lang)[0] || LANGS[0];
+function getHelpLanguage() {
+  const uLang = chrome.i18n.getUILanguage();
+  const lang = LANGS.find((l) => uLang.replace('-', '_') === l
+    || l.startsWith(uLang.split('_')[0])) || LANGS[0];
+  return lang.replace('_', '-').toLowerCase();
 }
 
 /**
@@ -337,9 +337,14 @@ function getLanguage() {
  * while respecting previous user acknowledgements.
  */
 async function updateHelpContent() {
-  const hlxSidekickHelpContent = await getConfig('sync', 'hlxSidekickHelpContent') || [];
-  log.debug('existing help content', hlxSidekickHelpContent);
-  const lang = getLanguage();
+  // don't fetch new help content for at least 4 hours
+  const helpContentFetched = await getConfig('local', 'hlxSidekickHelpContentFetched');
+  if ((helpContentFetched || 0) > Date.now() - 14400000) {
+    return;
+  }
+  const helpContent = await getConfig('sync', 'hlxSidekickHelpContent') || [];
+  log.debug('existing help content', helpContent);
+  const lang = getHelpLanguage();
   const resp = await fetch(`https://www.hlx.live/tools/sidekick/${lang}/help.json`);
   if (resp.ok) {
     try {
@@ -362,9 +367,9 @@ async function updateHelpContent() {
           return true;
         })
         .map((incoming) => {
-          const index = hlxSidekickHelpContent.findIndex((existing) => existing.id === incoming.id);
+          const index = helpContent.findIndex((existing) => existing.id === incoming.id);
           return {
-            ...(index >= 0 ? hlxSidekickHelpContent[index] : {}),
+            ...(index >= 0 ? helpContent[index] : {}),
             ...incoming,
             steps: incoming.steps
               .split(',')
@@ -376,6 +381,10 @@ async function updateHelpContent() {
       await setConfig('sync', {
         hlxSidekickHelpContent: updatedHelpContent,
       });
+      // remember when help content was last fetched
+      await setConfig('local', {
+        hlxSidekickHelpContentFetched: Date.now(),
+      });
     } catch (e) {
       log.error('failed to update help content', e);
     }
@@ -732,7 +741,6 @@ const internalActions = {
   // });
 
   await updateHelpContent();
-  await updateProjectConfigs();
   await setUserAgentHeader();
   await updateAdminAuthHeaderRules();
   log.info('sidekick extension initialized');
diff --git a/src/extension/module.js b/src/extension/module.js
index f1796c91b..7fe208786 100644
--- a/src/extension/module.js
+++ b/src/extension/module.js
@@ -251,10 +251,10 @@
     'fr',
     'it',
     'ja',
-    'ko-kr',
-    'pt-br',
-    'zh-cn',
-    'zh-tw',
+    'ko',
+    'pt_BR',
+    'zh_CN',
+    'zh_TW',
   ];
 
   /**
@@ -529,7 +529,9 @@
    */
   function getLanguage() {
     return navigator.languages
-      .map((prefLang) => LANGS.find((lang) => prefLang.toLowerCase().startsWith(lang)))
+      .map((uLang) => LANGS
+        .find((lang) => ((uLang.replace('-', '_') === lang || lang.startsWith(uLang.split('-')[0]))
+          ? lang : undefined)))
       .filter((lang) => !!lang)[0] || LANGS[0];
   }
 
diff --git a/src/extension/utils.js b/src/extension/utils.js
index 0a89c7972..98e4ccdbb 100644
--- a/src/extension/utils.js
+++ b/src/extension/utils.js
@@ -711,23 +711,3 @@ export function toggleDisplay(cb) {
     setDisplay(!display, cb);
   });
 }
-
-/**
- * Updates the legacy project configurations to the new format.
- * @deprecated
- * @todo remove
- */
-export async function updateProjectConfigs() {
-  const configs = await getConfig('sync', 'hlxSidekickConfigs');
-  const projects = await getConfig('sync', 'hlxSidekickProjects');
-  if (configs && !projects) {
-    // migrate old to new project configs
-    for (let i = 0; i < configs.length; i += 1) {
-      // eslint-disable-next-line no-await-in-loop
-      await setProject(configs[i]);
-    }
-    // TODO: remove old project configs
-    // await removeConfig('sync', 'hlxSidekickConfigs');
-    log.info('project config updated');
-  }
-}
diff --git a/test/extension/utils.test.js b/test/extension/utils.test.js
index 26e257d0d..b879e825a 100644
--- a/test/extension/utils.test.js
+++ b/test/extension/utils.test.js
@@ -335,17 +335,6 @@ describe('Test extension utils', () => {
     })).to.be.true;
   });
 
-  it('updateProjectConfigs', async () => {
-    sandbox.spy(window.chrome.storage.sync, 'set');
-    sandbox.spy(window.chrome.storage.sync, 'remove');
-    await utils.removeConfig('sync', 'hlxSidekickProjects');
-    await utils.updateProjectConfigs();
-    // expect(chrome.storage.sync.remove.calledWith('hlxSidekickConfigs')).to.be.true;
-    expect(chrome.storage.sync.set.calledWith({
-      hlxSidekickProjects: ['test/legacy-project'],
-    })).to.be.true;
-  });
-
   it('setDisplay', async () => {
     const spy = sandbox.spy(window.chrome.storage.local, 'set');
     await utils.setDisplay(true);