As a general guideline, I'd avoid asking questions for other people. If they have a question, and that reminds you of something in your own life, or is a problem that you expect to have, asking about your issue is fine. Although, if it's a problem you foresee happening in your life, you might have difficulty clarifying the "problem" enough to keep it from being closed as "unclear," or possibly "too broad."
In the interest of helping your friends that worry about their language skills in a second (third?) language: if it really is all that bad, you can offer to help them with the question, and the flood of comments, by setting a time, or a couple times, each day when the two of you can sit down and read the site together. That way they get help with their problem, and they get practice in some of the "finer" (?) points of the English language.
On many other sites in the network it might be reasonable to try being a proxy for someone else. With the twists and turns that feedback and clarification requests can take when dealing with interpersonal issues I doubt that you could know enough information about the question to be certain of dealing with all the comments and requests correctly.
If, on the other hand, you really do understand their problems that well, and you obviously know the cultural context like you own back yard, then you are probably the best one to answer their questions anyway. Thus, making the round trip through the bit-stream an effort better spent elsewhere.
