I attached an infinite water tank (EnderIO) to the cauldron, so it would be refilled directly after I cleared a dye recipe, so I wouldn't have to rightclick with water buckets all the time.

Except, this happened.

I filled the cauldron with water, added some brown dye, and rightclicked vanilla glass to dye it brown. As 125 mB of dyed water is drained from the cauldron, it is immediately refilled from the infinite water tank, effectively bringing it back to 1000 mB dyed water. I could spamclick glass to keep dying more water, and the dyed water was replenished back to 1000 mB.

If this is combined with a mod that lets you recover dyes from painted blocks, this effectively allows you to get infinite dyes from water. In other words: duping dyes.

This does not seem to occur with potion fluids however. Only dyed water.

Affected versions:
Minecraft: 1.12.2
Forge: 14.23.5.2860
Charsetlib: 0.5.6.5
Charset Crafting: 0.5.6.0

Water is meant to be infinite, and dyed water's primary use is dyeing items for aesthetic purposes. The behaviour should be configurable, I suppose, but I don't think it's automatically undesirable?

I would have to prevent any methods to extract dyes from dyed items. As it's a fully customized pack, that shouldn't be a problem though.

(Alternatively, accept that dyes can be duplicated in this way, and avoid using them for balance-critical recipes.)

Unfortunately, Charset is very low-maintenance nowadays... sorry.