I haven't read all the comments, so forgive me if I'm just repeating the same stuff (on another note, I hope I am).
This is a horrible idea, if you ask me. Language barriers are there because there are languages. If you keep supporting languages, there will always be language barriers.
English speakers, especially Americans, feel bad about "making people speak their language". I have seen this many times. But it's just ridiculous. We don't need more than one language. Having more than one language:
1) Creates a language barrier, thus slowing down advancement. 2) Gives people a reason for discrimination, just like nationalism, racism, and religion.
When you say that "If just one little girl in Brazil sticks with programming because an answer on this site helped her finish her first project, well… that’s not good enough!", it sounds like a really humble thing to do, but it in fact is the opposite. You are overlooking the fact that there's a lot of information regarding programming and many other things in many different languages already. I'm not a native speaker of English, and I learned English thanks to my interest in programming. First I started with reading stuff in my own language, then I realized that I could learn much more if I read stuff in English. And that's how it should be.
I don't care if it's English or any other language, but we only need one language, not three, not two, only one. The rest is just noise.
To wrap it up, disguised by a seemingly humble thing, you are supporting language barriers, by supporting languages. I'd expect better from you guys.