Ill take everyone’s word for it then that its hand placed
As far as uniqueness, that’s the point, some of the lairs are not unique. Some caves look well designed, others look like a random walk with textures painted on, and that is fine as caves should, and a few are similar enough as to be identical (putrid caves, dump and warf, for instance). The wardens lair is unique because its the only one, but every corridor is made up of similar repeating textures, nothing that couldn’t have been done randomly. Not inherently unique as though its all hand painted.
As far as making sure everything works, you do that by a set of constraints on your random generator. Exit must be at least X units from the entrance but no more than Y, main path must be at least so many units long but not more than so many units, must not cross it’s self, must connect to some unique premade cell, etc etc. With enough constraints you could ensure that every roll of the dice is sure to produce maps that are similar in size, theme and distribution of objects but are varied enough to make for a different experience each go through.