I've noticed the game can be pretty buggy when you enable mods half-way through the game, especially after you've discovered the library - basically a bunch of things have been edited throughout the course of the game causing massive conflicts.

Have you tried starting a fresh save with the mod enabled and progressing from there? (If that still doesn't work, please tell me!)

Great idea, but the game seems to error out whenever I try using the sword/boomerang on a signpost, with the following message:
Data/Content/Global/Actions/BeHackedAction.lua:69: attempt to index field 'material' (a nil value).
I currently don't have any other mods loaded that could cause interference. Are you seeing the same thing on your end?