Saw some people reporting an issue and poked around in the code for a bit.
Decided to change this
"C": { type: "block", code: "game:crock-burned-east" },

to this
"C": { type: "block", code: "game:crock-burned-*" },

To make it more resilient or to fix whatever issue people below me were having, it seems to be working fine for me so far. Though I am on a Singleplayer world.. Iunno.

Give it a try, couldn't hurt.

Further observation by another player on my server - fire clay crocks cannot be sealed at all by either type of clay.
Edit: I've now confirmed this myself.  Only blue-grey crocks can be sealed, and the clay is not consumed.

I can confirm Toasty's observation - this is currently allowing crocks to be sealed without consuming any clay

nice mod but i dont lose the clay. Is that on purpose?

Brick very true! You could almost have a crock of cooked food last indefinitely. That might be a bit game-breaky, though... although, with having jam, pickled veggies, and salted meats. we're not that far from "Canned Food".

Cygnusia Technically if you bake a crock again with a clay seal, you gonna make pasteurisied canned food that should last much longer than crock with normal wax seal but without pasteurization in a sealed vessel

This isn't a bad idea. It's definitely doable, although with clay being a porous substance, maybe have a shorter shelf life than conventional sealants? Possibly bake the crock again to cure the seal and make it air tight? Just spitballin' here. 😄