I’m an European guy living in Japan that browse tech documentation in English. I’ve the same issue than you, sometimes MSDN or MDN pages are returned in French (all my devices UI are in English, with French locale). If it were good French, why not, but it’s crappy MT instead. Have so respect for the user please. Sometimes I got Japanese thrown at me, depending on which network I’m connected.
Finally I sometimes perform search in other languages, for instance Chinese. Of course I got results mostly in Japanese from Google... few years ago it was possible to change the language for a query, now the settings in burried under dozen of clicks, and are link to my profile. So basically unusable.
In a way it’s like the OS desktop UX: developers are busy trying to outsmart the user, yet the end result is more painful to use and less customizable than it was a decade ago.