If it isn't a real language, that's a whole other set of circumstances. If it is a foreign language that is actively spoken, and the police have a reasonable wa

If it isn't a real language, that's a whole other set of circumstances. If it is a foreign language that is actively spoken, and the police have a reasonable way to get the document in question translated, you should have to help them. However, if they don't have a reasonable way and you are the only one that can help, then you could be compelled to do so. It is a question of what's reasonable.