I have the same problem. Starting 2 day ago all my notifications are coming in Russian language. At least you understand English but I don't understand any word of russian. Sorry by that because I suppose you are looking for a solution that I can't give you
I have my profile set up for all emails to be in English just as you outlined. Newsletter is in some language I don't recognize. All other emails are in in English. Also, my son says he got the last newsletter in a language other than English, also. Is this a glitch that will go away are is there a problem that needs correcting.