Hello,
I like the basic structure of this puzzle idea but I don't like few things like the stealing part. It can be very annoying for player. You just stole an item and then it's stolen back already...
Oh noes, now we're moving on some very dangerous waters - If you don't like the stealing part, which most probably leads to its removal, it
must be replaced with something that isn't as annoying but still does the job.
Because if you remove the stealing part, there's no reason why the player would want to eat any of the pouches of crystal dust before collecting all of them, for there's no chance of losing them by any way, were that the case.