This might be a bug report, it might be a design feature. Not sure.
Conceptually, when you are creating a random girl (.rgirlsx), you can specify if she's human or not. You can also specify where she is found, either in the catacombs or elsewhere. And conceptually, these two attributes are orthogonal.
But I'm pretty sure if you design a random "human, found only in the catacombs" girl, you have a zero percent chance of her actually showing up. I find it extremely non-PC, that in a game with frequent gang killings, rape, and torture, that the catacombs are for non-humans only. Specie-ist redlining!!
(Yep, that's sarcasm - but I would really like to be able to find humans in the catacombs, too.)