Seems like a pretty balanced "this is good, this is bad, choose it if you want to role-play something challenging" option, in my humble opinion. Something that you don't like that is working as designed isn't exactly broken, so what's to fix?
The zombie trait seems to be more of a geomantic over-investmetn that an undead state, so not playing nice with a witchcraft spell isn't really surprising. I didn't anticipate it when I ran into it, but it made sense after a moment of being startled.
