I was trying to alter this mod for 1.12.2, just some minor changes for myself. I got the workspace all set up and there was an error that showed up instantly without me changing anything, and I was unable to find another solution. Would you know anything about this?

It seems pretty important, and hovering over it says the field GuiIngame.persistantChatGUI is not visible.

Looks like the access transformers did not load correctly, try running setupDecompWorkspace again

Nothing changed, if I were to rebuild my project with a different forge 1.12.2 MDK do you have a suggested version?

No idea what's wrong, check the gradle logs, maybe they have some info.