Unfortunately, there is a bug being caused by a missing image file that renders spells unable to be cast and the game crashing after combat. Looking it up it looks like the Timed Attack Core is missing its input arrow graphic file. Based on me hitting the same issue in my experience, the image file was probably discarded when the project was deployed from RPG Maker since the thing that auto removes unused audio and graphics does not have visibility on resources plugins are using. At least, not on MV, if I am remembering right, so I imagine MZ works the same.
I couldn't get super far because of that, but I really enjoyed the custom enemy sprites! Custom sprites and monster designs always get a big thumbs up from meeee 👍