Ah, Gilbert, perhaps that would work, if there were only one sign language, but there are many. I recently met a guy who works as a signer for hearing impaired people, and he was explaining the difficulties of a deaf audience from a variety of different spoken language communities. There are apparently even enough differences between the forms of English sign language for it to cause problems. From what he had to say, I would suggest that the signed languages generate just as many issues as their spoken counterparts.