It seems like JEITweaker-1.0.0 is non-functional.

I've tried using it like this:

mods.jei.JEI.hideItem(item);
mods.jei.JEI.addInfo(item, ["This item is disabled.", "If you somehow obtained it, please report it on Enigmatica 5's issue tracker.", "There's a link to it in the Main Menu."]);

No errors, but nothing happens. The item was of course an actual item.
logs.zip

You uploaded an empty zip file.
also please don't give me files to download, pastebin the logs

Alright, sorry about that.
crafttweaker.log: https://gist.github.com/NillerMedDild/e5e920917d4910f61fd2a8b7123ca060
latest.log: https://gist.github.com/NillerMedDild/88ba3c9c2f484b00091ad2a6f681d2bf

i have same issue, but with error no such member
logs

@RIKRUS
Please update to the latest CraftTweaker beta release on CF, that issue should've already been fixed in there.

i have same issue, but with error no such member
logs

thanks, it works

Kindlich helped me out, it works fine if I call it normally, outside of loops, so user error - Sorry about that.