Welcome to releases! Though, there may be levels where the lack of an exit winds up making you unable to clear the level with the lack of the ability to backtrack from it. I suggest making the exit serve as a teleporter, which may not be foolproof, but should make more stages compatable.
There may also be issues where a level is unable to be completed because a token is on a character-specific path. This occurs as early as GFZ2. May be best to allow for a minimum token count for completion instead of forcing to get all of them.