They've mentioned in the Discord server that the game is roughly 50% done, maybe 40% but I might be wrong.
Also the curse undergarments is only active in the forest area. Once you leave the forest they become inert. So just put it on right after you save the ranger. You'll get a scene for trying to leave the forest as well as another scene for figuring out how to take it off.
After that you can give it to the Wizard at the Inn to purify it for personal use.