Creating a native terrain for the Dungeon

[Fellow Human]

With the limited abilities the map generator has, I'm struggling to create a map with all 8 races present with their native terrain as their home town.
The issue is with the Dungeon. Their native terrain (called underground or something like that) doesn't penalize their movement unlike it does to other races. But it only spawns, well, underground. I want to avoid the underground layer because it will automatically put half of races, four out of eight, in there while only two (Inferno and Dungeon) seemingly can have native terrain there. The other six races will be out of place underground.
I still can't believe the in-built map generator can't create a random map that places each race in their own native terrain. Is it like that indeed?