Had the same thing happen to me; but the menu option didn't seem to work. Also some details like the decayed Wormboss in the background didn't load since I loaded a save from just after defeating it. I actually like this so much I'd gladly replay it to also not miss on updated details earlier in the game but I can see how that'd take a toll on some players who aren't into replaying stuff. Amazing work! I'm following since Ghoulies <3
There's no *official* name for the character yet. We'll get to that on the lore update, which is probably going to be the next one down the line.
Technically, the files are named as Mustard, but we'll see where we go in the end ^^
Also, yeah I had fun doing that little feature in the difficulty menu. Glad you found it :p