@hekazu Going to be tagging you like this pretty often to throw questions at you. This time, it's:
Would it be possible for Kenza/Mistletoe to open the cell door with pieces of the wooden tray? Depending on the type of wood and how brittle it's become with mold, it could still be enough to stick into and maneuver the lock so that it opens. However, you're the GM and I have no idea what kind of call to make so I'm passing the ball to you xD