The codebase is a mess and was initially created when I didn't know squat about Minecraft's internals, and even after murapix' event system PR I am just... fundamentally unhappy with the design of it. There have been plans for a rework here, however due to time constraints, fears of feature creep and general burnout those plans never come to be. If you're on 1.18+, I recommend using Lychee instead, and if you're on 1.16, the mod should still for the most part just work:tm:, plus there may be maintained forks, or other ways of achieving in-world crafting (I will temporarily unarchive the repository and add those to the README here if applicable)
Note: If anybody wants to carry on this mod before the event system PR, the last commit I recommend for that is this one, which should be a pretty good basis for forks (the commits after that were meant to be the start of this mod going multiplatform, but I never really got anywhere with that just because the mod itself became too iffy to work on)