About changes and/or combining Hero Specializations.

The problem with NHF is that the scripts must be enabled on the map, so the map files are run through a special program before the game.

As I understand it, this program itself is in an executable file, and a set of maps is run through it. If you need to add heroes from NHF to your map, you just need to add it to the executable. As I wrote earlier, complex special abilities, like the one described above – a mix of Nibros and Krag's special abilities – cannot be created with standard scripts.
In my future map for Kaspar, I initially wanted to give him a combined special ability – his tent ability + a special ability for liches (like Lucretia's ability for vampires), but I abandoned this idea because it cannot be done with standard scripts, only through manipulations with the exe file. Maybe I don't know some nuances, and it can be done more simply).