99% of the stuff we're fixing is text bugs. Misspellings, grammar, punctuation, etc. The other 1% is in images and video. That's not to say that there's very little work going into editing images and video, because that takes a lot of effort too.
None of the fixes require modifying anything about the save system. We all keep multiple save files and load older saves to check fixes. Checking fixes doesn't slow us down at all.
It probably seems like it's taking a long time because this is an RPG with a lot of text, and there's a lot to look through. We are all trying to make this the best it can be, so we're not cutting corners.