I only just started to take another serious shot at this -- work has been too busy and I ended up having to restart from scratch after the battle bug fix.
I ran into another (much less serious) bug: Somehow, my new save inherited some (all?) of the cooking recipes my old one had. When cooking first unlocked, I had double copies of the initial recipes, and still had access to late-game recipes I know I shouldn't have had. For comparison, I extracted a new copy of the game with no existing saves; playing to the same point didn't produce the behavior.
(It smells like some sort of NG+ feature misbehaving. I'm not complaining that much, as it will make it easier to reach the point where I had to restart. But I worry that if cooking data was retained, whatever corrupted the save might have been retained too)
More pleasantly, I did a double take at the Christmas easter eggs. "Why is silent night playing....? Why is there a Christmas tree where there wasn't one before...? Oh wait...haha, that's hilarious and fantastic."
[edit: Actually, I've noticed battles crashing on start a lot more than they did before....but I played the first few hours right after the bugfix release and it didn't happen then, so I think it might not be the game's fault. Unless there's a Christmas effect in battle that could be bugged.]