I'm an App developer, and all my Apps have been developed in English so far.
I know I have a lot of international users and not all of them understand English well. I know this because they email me, and sometimes, I don't understand their question or comment. (Google translate has helped a lot. haha)
So my question is, how much value is there to add additional languages into your app? (this is a productivity App, as long as my user is aware of what the three buttons do, there's really no need to understand English. Only problem is when they email me for support..hehe)