ItemsAdder is not blocking recipes with Netherite ingots, it would have no sense to hardcode this check.
CustomCrafting developer stopped being collaborative on fixing compatibility issues long time ago, seems for him easier to blame other plugins than working on a fix together like we used to do before.
He probably thinks that his plugin is the only one custom recipes plugin available on the market, which clearly is not.
I am trying my best to keep compatibility but I can't say the same thing for the other party.
Not the first time I hear him washing his hands on this kind of issues, I'm sincerely sick of having to deal with that kind of behavior as I'm always trying to be collaborative with other devs.
This developer is known to change CustomCrafting API on each update, this required me to update my code multiple times during the same month but I've never blamed his work, I just updated my plugin to fix compatibility.