During the installation, the mapeditor settings are going to change, so the new minor nations's units will be available to use.
In addition, there are a whole lot of new field sets are included to make the map editing easyer and faster.
To use them, click on the "Terrain" button, than "Browse"..open the: scenarios/fieldsets/ folder, select all of the elements from the list, than
click on "Available fields:" to generate.
In the mods/HRA/data folder, there's a bridgevisible.pak file. This file is only for map editing. It makes the path of the water crossing units visible in the mapeditor. I recommend to remove this file before you play the game!