I guess for follow-up, I'm fairly certain the saving issues were related to the UII+ losing communication with the USB drive. I did switch over to VICE to finish the game and no real issues after that.
The game locking up with a white screen after casting the spell for the first time I think is still legit, although I couldn't tell you what unique conditions I might've had to replicate it.
Thank you again for making the game and I'm sure to play the sequel at some point!