As I do not recall and cannot find in this thread any comments on the name of the hill, I don't see the point here.
But Celia's pretty disgusting death account is hardly the core of The Cocktail Party. It is about several other people as well, and for Celia, it is really about choice. It did not need that gratuitously horrible ending. I can only assume the crucifixion was meant to evoke a Christ-like sacrifice, but even Jesus was not upside down on an ant hell. And crucifixion alone is horrific enough without those gory added images--even if there were any reason to have "natives" doing a crucifixion--one that seems to outdo the Romans and Jesus in its pointless violence.
But details matter. Any good, let alone "great," artist is so because of the complete work, not some abstract message or "main focus" as if it were a statement. Imagine "Heart of Darkness" without that white thread or Mrs. Dalloway without her flowers or Burnt Norton without the bird. It may well be that the accumulation of rich and resonant detail is what makes any of them work (I'm speculating, as I have not worked on this as an aesthetic).
I would be interested in anyone's view on that last idea.