I might try to find a way round this. Let me know if you think it is worth the effort.
first time heard about the project, and it seems to be interesting one, but i do not get the point how you would help posters with their English?
English is not my first language, i actually did not ever learn it throughout my life, but have enough knowledge to do even Business in English, both writing and speaking, and also reading books/articles in English, so it is not that hard, if you want. There is English everywhere around us, you just turn on the TV, and watch any program without subtitle, and it will stick to your mind.
I had learned German and Russian at school, and Hungarian in the course, but could not use it even close to English in everyday life, and do think that it is just because English is everywhere around us, and it is widely used in Travel and Business.
back to subject, do not think that people will learn to speak English, or even write, in a forum IMHO, they need speaking incentive, and there is a bunch of applications that provide that, would mention duolingo, which is free and easy to use, and could help anyone to learn basics of a language, and faster than school or course
long story short, seems like an interesting idea, but i do not see it as successful one, especially if you need much time for administration, it is not worth the effort