I saved the Steamapps/common/Refunct folder before it updated, which, according to some of the forums I've been looking at, should allow me to downgrade back to Update 4(?) and do runs of NGG. Do I need to do anything else? Any% w/ NGG was my favourite category to run and I still wanna do it, need to be 100% certain that this will work for it, so if anyone knows please lmk

There was a new patch released that adds a "glitched mode" that is the same as executing the glitch was before. You can access this glitched mode by pressing and holding crouch button before clicking New Game in the menu. For the time being, you are free to use whichever version of the game you like, old or new. That said, this rule could change in the future.