Very unique mechanic with the swapping brains! One suggestion I’d have is, instead of asking for rerolls in a table, you could simplify this by writing all names in index cards and sorting them, or just having numbers in folded papers in a bag for players to pull from.
It seems like this adventure would be quite challenging to run, but super fun and unique. I think it would be a blast to see the PCs mostly swap their minds between themselves, and suddenly one of them starts acting like a black pudding while their mind is transported to an ooze in a jacuzzi.