I will try to get a post out this weekend, then.

My main problem with it still being called Pthumeru would be that it would make it weird for the twisted semi-undead from the old labyrinth to be called "Pthumerians" if "Pthumerian" could actually refer to [I]anyone[/I] from the country. It is strongly suggested in the game (if not downright stated, but I can't seem to find any references to such a statement) that "Pthumeru" fell long ago around the time of Queen Yharnam and the stillbirth of Mergo, which would make the current country more of a successor state.
Eh... the more I look into it and try to see patterns in naming, the less certain I feel that I could come up with something original that would fit. I'm thinking it may be best to call the country something derivative from Pthumeru, yet different enough that the people of Yharnam don't get confused. I was thinking "Pumeria".

EDIT: Had time to properly read your post now, Decimate, and I must stay that I'm both intrigued by Ludolf's dream and pleased with your writing. Well done.

EDIT2: Decided not to wait, post is up.