NHF – new heroes for Heroes V 3.1.

I wish I knew the fundamental difference between this mod and those made by Goose.

Does version 0.90 mean that there are unfinished, basic elements, such as missing icons, crashes, imbalanced parameters, etc.?

Here, the mod was created by mapmakers and scripters. This is both a strength and a weakness; scripts allow you to create truly cool heroes, such as a necromancer who turns enemy cities into undeveloped Necropolises, or a demon who opens portals on the map.
But there is also a downside - the maps must have these scripts activated. I have had cases where I discovered that I was playing a hero who could do nothing... the scripts were not working... I don't know how it is after the transition to MCCS, but in older versions, a separate program was used.