@rfellows suddenly I understood what you mean. If we will use "common-ui/jquery-i18n" and call $.i18n.browserLang, you'll get null. I didn't find any usage of this method in code. However, we can use "common-ui/jquery-i18n-properties" for this functionality, or I can add new method like $.i18n.browserLangReal() in new "common-ui/jquery-i18n".