Possible yes, would I be able to do . . . I'm not sure. Part of what makes me able to successfully expand on what Tamur did is that I'm very familiar with the quirks of traits/ancillaries; however, I don't know a whole lot about scripting so it would make it quite a bit more difficult to do.

And in case I wasn't clear in my last, and when I re-read my post after seeing yours I don't think I was, the custom buildings/settlements/etc that I'm talking about are just the condition and excludedcultures checking. The current version either checks against a hardcoded list (cultures/factions) or doesn't check at all (settlements/buildings/units/etc) because it makes no sense to check against vanilla values.