I don't see anything wrong, it should work all perfectly. Does the coordiates NW/SE are temp?
Yes the NW/SE are temp, actually the entire world is temp. Most of my experience working with worldspaces is from duplicating vanilla FO3 to build my glass windows cells in DCInteriors. I was helping someone figure out where they went wrong trying to generate LOD and, they passed this off to me, I've ben playing with it to learn more about scratch building worldspaces.
It's not a mod I'll ever release because it's not mine but, is proving a fun learning experience to play with the landscape and, figuring all of that out.
cev