Unfortunately the gallery is saved in the registry so you can't unlock it using the save file, just through playing + cheating in other aspects. If I understand correctly your current original save file was corrupt...(?) Can you try creating a new run, saving it, and then modifying that save?
Both the original and the copy of my original get corrupted if I mess up either save.
I tried doing a new one with chests and it eventually goes corrupt. It's nothing crazy either.
EDIT: so i just maxed out everything in the beginning and didnt change much during midgameplay and it seemed ok after that but i still kept a copy of my file in case it messes up. I almost got all the gallery scenes