Look in your extension if you don't have one replacing the firefox number version .An extension like that : https://addons.mozilla.org/fr/firefox/addon/user-agent-string-switcher/?utm_source=addons.mozilla.org&utm_medium=referral&utm_content=search
For have translation ,you just have to download the extension Firefox translation . https://addons.mozilla.org/fr/firefox/addon/firefox-translations/?utm_source=addons.mozilla.org&utm_medium=referral&utm_content=search
That's idios , every navigator allow that but no Firefox .If they add this function please make us able too not have pub.(You can cast Firefox on your Android phone using screen sharing but you can't do anything)
