Holy crap, that's a lot of work.
What about just tagging articles in cur and old with a language code ('en', 'fr', 'akk'), and putting them all in one big database?
Users' interface language (the navitorial stuff) is determined by their browser settings.
That doesn't solve the problem for other wikis (-tionary, -books), but it does cut down on a lot of differences. Also, it makes interwiki links a lot easier to detect and fix.
~ESP