The maps only have scripted names added to some objects and a link to the script file. There are no other changes in the map.xdb file. And, of course, NHF-Names.lua has been added. But how could this affect the accessibility of portals?

Added 1 hour 17 minutes ago
I suspect that portals and ladders don't work because the mobs are standing 3 tiles away from their position. The mod provides for a maximum distance of 2, although even at 3, the monster prevents passage.

Added 2 minutes ago
Here's the diagram:

B B B o o o
B B A o M o
B B B o o o

M - mob
o - guarded by a mob
B - blocked ladder cell
A - active ladder cell

Even though the distance between the center of the ladder and the mob is > 2, all free cells adjacent to the active ladder cell are guarded by the mob.