Ok, so go to lines 20129, 20326, and 20523 of export_descr_buildings.txt and change where it says,
Code:
culture_dunedanic_3 requires factions { roman, berbers, } and hidden_resource not_exist or factions { roman, berbers, } and hidden_resource nofort blah blah blah...
and change it to,
Code:
culture_dunedanic_3 requires factions { roman, berbers, } and hidden_resource not_exist or factions { empire_east, empire_west, berbers, } and hidden_resource nofort blah blah blah...
Not that this will only remove the ability of Adunabar to build these buildings (both as AI and player). Removing the abilities from effecting them, making the changes visible (it will still appear in the project browser than they can construct them), or preventing the AI from building them while allowing the player to do so would all require many more changes.