The usedunique editing is the only way to edit the status. Otherwise, your best bet is just importing. Any characters it thinks are fine will just respawn at their original locations, at the cost of losing any prisoners you had.

Otherwise you don't want to import, this post is about as step by step as the editing can be.
https://psteamcommunity.yuanyoumao.com/workshop/filedetails/discussion/1358096888/3396301606644476289/#c3396301606644621739

If you're having issues, I'll need more info on what you don't understand or can't find. So that I can try to elaborate further.

Hey Shidan, thanks for the quick reply!

So I did try importing the game, not importing NPC,s so they could be alive again. I managed to change the stats of one of my squads as a test, and then killed the Thrall Masters along with the chiefs of the Broken Finger and Skull Drinkers tribes. But when I talked to the World State Checker NPC again, it still showed them all as alive or okay—no change at all.

Oddly enough, I tried the same process with the Meatlord, and that one worked just fine—the world state updated correctly after I took him out. So now I’m thinking maybe this issue is only affecting minor faction leaders and not the main ones?

I'm planning to start a fresh save just to test whether this is a consistent bug or something weird with my current file.

As for using the FCS, my main problem is that I don't really understand how to connect the usedunique states to specific factions or NPCs. I can find info like the GameData string of a faction, but I don’t know if that’s even what I’m supposed to be looking for. When I tried searching for entries under “camera” (like some guides suggested), I couldn’t find anything that matched.

So the "usedUniquesStateX" entries are referred to by number, this number is assigned to specific character up above in the camera entry. Alongside a bunch of handle values, you'll see a "usedUniquesX" values, where X is a number. That number connects it to the "usedUniquesStateX" below, whatever one has the same number.

So for example "usedUniquesState7" and "UsedUniques7" are connected, because they are both 7.

As for connecting to a character, that is handled by the "usedUniquesX" value. To the right it will give some sort of ID, referencing a mod file (e.g. 97095-rebirth.mod). This ID is the character.

You can figure out what a character's ID is by opening a mod in the FCS instead of a save file. If you go tot he characters section, you can open any character there and see near the top they have a "String ID" value. This is the ID that the "usedUniquesX" value references.

So to edit a character's state you need to locate the ID of the character in the list of "usedUniquesX" values, to figure out what its X number is. Then go down to the "usedUniquesStateX" values, and edit the one that is connected to the same X number.