That was more me thinking out loud lol I'm aware you don't know the itch app.
So, I checked my files via app -- this is the basic setup:
I didn't really see anything 'save' related beyond 'save location'. If you could reconstruct my save, that would be amazing; I sent a friend request on discord. But even if I'd have to wait a year for everything to be done (and I'm mainly here for the main girls to be completed), I'd just take the loss and be patient. I checked one of my other app games and saw that those saves were lost too/the game reverted to the beginning like YU did, so I'm pretty sure this was a 'itch app update' issue -- nothing else makes sense. Gonna contact them and see what's up there. Thanks again for all your help!