went to other side of downstairs (approx loc -1312, 999) and after killing ancient caretakers, this one spawned in front of us. so guess mob does spawn.
we pulled dead-end room (downstairs, NW most of the zone) and he was in the mobs.
edit: went to other side of downstairs (approx loc -1312, 999) and after killing ancient caretakers, this one spawned in front of us. so guess mob does spawn.