I had been pondering a while how to tell if a civ is eliminated, and I was thinking today about how to look for it, and then it struck me: if a civ has 0 cities and 0 units, they're eliminated! I don't know if that's what the game keys on, but it should be good enough for cia3, and I have those per-civ values exposed in Lua already.
It's probably a minority case, but don't forget that under, Scenario Properties, an AI Civ can be set be set to "Respawn."
- Much more importantly, the work you've been doing is brilliant. (It really should be martini glasses ... )