My situation: I am in Switzerland. I have a Swiss French keyboard. I have English software. I use European dates. I read and write in English UK, French (Swiss and French varieties), German (Swiss and German versions), Italian (Swiss and Italian). I only want one keyboard layout except perhaps occasionally a US one for an emergency remote access situation.
With Windows desktop and the Desktop Office apps this now works, but with Office 365 it does not at all and Edge is very unstable. Chrome is fine at detecting language but O365 (now I see it is called Microsoft Editor) is useless.
Edge is OK too EXCEPT that is if I change the editing language in say Outlook online manually, then Edge removes all the other languages without telling me and I have to keep going back in settings to turn them on again.
I can possibly see that a user profile on a shared computer the broswser settings should not be shared between users, but as a starting point I need to keep ALL my languages active and if I am prepared to share my data have them autodetect. Going in settings for every email is not a solution.