Couldn't they? By your own admission, you've seen signs of their presence here.

( but perhaps she's right and perhaps they're genuine in their naïveté. given the state of this place it's difficult to imagine anyone living wandering these tunnels. certainly not for some time.

but that just begs its own questions, doesn't it? questions like just what they could have been trying to accomplish here and how the coven could have simply forgotten their involvement. )

Did you see the pools? The ones in the upper level?