[devnulloverflow]

> [Brussels] is French speaking, although it's in the middle of a Flemish province.

This is what I keep reading, but when I visited there I observed both languages in apparently equal measure. Of course my observations were superficial -- I was a tourist who spoke neither language.

But I even if I am right, that just underscores your point. The fact that a request comes from Brussels, gives you very little clue what language the user wants. Especially if that request comes from a some foreigner working for the EU.