I am logged on to Google, and they know I want English results and an English interface, because I've gone through and done all the settings. And yet, occasionally something goes wonky and they start showing me the interface in Italian again.
I have no problems if their default is the local language - that's pretty much a no-brainer - but when I've told them in no uncertain terms what my own preferences are, they ought to respect that.
Same here. I travel a lot and use VPN to access the corporate network. So if I am in the Chinese office google goes Chinese (and it takes some random guessing to switch the language back to English) then in the hotel (via VPN) it promptly goes German.
One small improvement would be to write the name of the language in the original and not in whatever country's version. (e.g. English instead of Angol, etc).
It randomly flicks in and out of German for me all the time (I live in Germany). I have ravaged the settings to change this, but to little effect. At least I am gradually getting better at German!
For some reason I tend to get Google's authentication pages in Hungarian (at least I think that's what it is), despite being in Sweden with sv_SE/sv/en_US/en configured in the browser and Google's services set to use English.
I have no problems if their default is the local language - that's pretty much a no-brainer - but when I've told them in no uncertain terms what my own preferences are, they ought to respect that.