Translator can be use to follow up on discussions that may seems interesting to a member just to have knowledge about the topics that is been discussed, it will not make sense if a person who can't speak or understand the language of a particular local board to use a translator to participate on that discussion because sometimes translator can't give proper meaning of a language, this can also be a problem for members of the local board to get better understanding of what is been translated.
I haven't thought of it this way until about now and it's very true. You know, translators focus on giving meaning to individual words and words could be contextual. In fact, some languages though spoken forward is interpreted from the rear to make sense (I don't know if you guys get the message I'm trying to present here and I wish you do). That could be the case and participating in such a people's discussion could lead you astray and also, set some confusion to what is being discussed.
There might be no rule restricting a users encroachment on other nation's local board but for a discussion to stay the course of its people as per how they are mostly affected and would help them the most, I think it should be reserved for the locals only. By locals, it doesn't mean of the particular origin but, being surrounded by the same environment or boundaries.