I just discovered that the 3D Editor (uh, I think I have the latest version, but I haven't updated in, like, at least a year) doesn't reproduce a graphic glitch that appears in the real game.
If a corner of two walls is on a spot that is elevated, BoA shows the cliff in the next room over, though the 3D Editor does not. See Nobody's Heroes, town 6, space (25,21) as viewed from, say, (22,24) as an example.