I was in the middle of saving a lot when my PC got bumped and shut off (I need a new power supply).

In-game, I'd just moved out a Sim (bringing the household to 2) and it was Monday in-game.

After loading the game back up, I went to open the same household: On the family loading screen, it showed 2 Sims (so, excluding the one that I'd moved out as though she'd be in the family bin, which she was not). When the lot finished loading, it was Saturday and all 3 Sims were present with portraits.

It looks like my game reverted back to the previous save, but I'm concerned about that Sim not showing up in the loading screen. Is there any chance that there are files that were partially saved/corrupted, or is it safe? I have all the important stuff (NPC files, etc) read-only from when I installed the game. Mostly concerned about the 'hood itself.

I used the Hoodchecker, which only came up with the usual Relationship stuff: Neither Sim exists, First Sim doesn't exist.

Do you have a backup? I would use that. Also, delete cache files and neighbourhood manager file inside the neighbourhood folder.

My most recent backup is about two weeks old, so I can pop that in.

I will delete those files! Thank you.

Your game doesn't save everything at once, so it looks like the loading screen was updated, but the actual game wasn't. I had that happen as well once, my sim showed as a toddler on the loading screen, but was a baby on the lot. Restoring from a backup is the safe option, but it doesn't necessarily mean that your neighborhood is corrupted.