Howdy! My Discord issue is probably because I'm using it wrong. I'm like that.
However, I've just now redownloaded the 1.0.2 build and found the Galaxy Door/Key interaction - with the door in the 'Inverted World' - still spits you right back out. Though, this was from grabbing the first available Galaxy Key (south of Pule) and booking it towards the lab to test it. So, barring a full playthrough or me getting RPGM:MZ and checking myself, at least that still seems borked.
Additonally, while I can't say for certain as I've since deleted the original .zip, cross-examining many files between my earlier directory and the latest (dates last modified + browser history) suggests I was on 1.0.2 when encountering both the Galaxy Door and Wet Spellbook bug. So I would assume the Spellbook issue still exists. I'm too lazy to do those more exhaustive things though...