So, after spending way too much time banging my head against the mac version flat out not working anymore, the conclusion I reluctantly came to was that this isn't going to be solved in a weekend.
I've discontinued the mac support for now, and a bunch of googling reveals that while I can't issue a refund for the mac games, you all can request one through the normal steam process:
https://support.steampowered.com/kb_article.php?ref=6695-QIKM-7966
Hopefully I do figure it out but it isn't going to be something I can do all at once without shaking myself apart. There's a LOT of complicated stuff going on here.
I am really sorry for the mac users (I know there are a few of you looking forward to this). Hopefully I figure this out before LOMAT comes out...