I just tried changing recipes for some of the nullifiers by using CraftTweaker. It adds recipes but refuses to remove them. I assume like that is because the recipes in this mod are not in .json like the new vanilla recipes etc.. Sadly I am not a modder and have no confirmation for that, but I hope it is possible to solve this issue as I really would like to nerf the Overflow Nullifier...

EDIT: Forgot to write down the versions.

UseNull: usefulnullifiers-1.4.1
Forge: 2575 for 1.12