https://bytebin.lucko.me/rDSxfJ6wXI

Hmm that would make sense as that mod uses Block Entity ontop of the vanilla caldron meaning it would be quite broken. Technically that mod just adds the ability to Dye Leather armor in cauldrons which Jello also adds and expands upon with the ability to Dye Dyeable Blocks.

Ill see what I can do but It may just be impossible and a hard incompatibility.

Internally Jello could never work with it as the Block coloring requires that a certain DyeColor ID is stored within the cauldron to Dye Dyeable Blocks and it is impossible for such to play nice with color mixing for certain reasons. As I also add a Block Entity to cauldrons, It also impossible to have both work for the same block sadly.

You can still color mix with Jello by changing the color of the water and then dyeing the leather armor as it supports color mixing in such a way but not within the water.

Ill mark this as a Incompatibility within the Mod internally for future Updates and I wont close this till such has been push to info People of such

Marked Incompatible in the latest Version 3.2.1+1.18.2