This patch is wild. I'm loving it. But...
For me, once I try to get to the preparation screen of Chapter 20 (darkling woods), the game freezes and it never takes me to the prep after all the cutscenes.
Additionally, Wyvern Lord axe animations cause the game to crash. I've turned off Cormag's animations for now, and that's fine; but I'm pretty sure there are animations out on the open source you could just port into the patch?
Also, for me, Chapter 19 was ENTIRELY BLANK. No enemies. No reinforcements. No boss. I just spammed the "Wait" command for 13 turns. Probably wasn't an intended feature to give the player a free chapter of what is probably the hardest chapter in the game.