One thing that sort of puzzles me, is that sometimes "Rakzum's illoyal servant" is there, and sometimes he isn't.
First thing I noted it the thought was, maybe he was missing in one "instance" and there in Another (some kind of design slip - maybe he was supposed to be removed but was left in one of the instances), but then later I start to Think if he appears when one of the bosses are killed. Long time ago someone told be about Another NPC, in the same room as Shkah but when I Went there to look there was none there - maybe it's Another NPC that appears there at a rarer occurance (when Onard is killed?).
One guess was that something was supposed to happen after "x" numbers of bones were purchased. A wild thought I had was that you could use the bones as some sort of decoy for Chalte, but I didn't see any obvious "hot spot" and it doesn't seem to be be possible to drop items in the Cave (possibly apples to all instances).