Last year Mark Herschberger developed a first prototype of what he called Multilateral, Asynchronous Bidirectional Synchronisation (MABS). The prototype did work, but it did not go much farther because time and funding - the project is now on hold (and I’m not entirely Mark got around publishing all his code, I should check with him). 

As for getting additional languages, as Emmanuel said there’s a bit of work around selecting and preparing the content that should go on a WikiFundi instance. This tool was initially developed to help teach editing, and thus goes a bit further than just slapping a copy of Wikipedia on an offline Mediawiki. We certainly could prepare more than just the currently available French and English versions, but that’d be more labour intensive than simply pressing a button and would require a bit of funding (not much, but still).

Cheers,

Stephane