The nifs in question have no assigned texturesets at all. only materials which use a remap diffuse. You can override the remap so it works as a normal diffuse, however, it has issues. You lose roughly 40 - 50% in building colour variation. There is also tiling issues if you do. Example. 1 building in vanilla is pink. If you override it, 1 of its 2 story walls (which for the sake of discussion is 3 tiles long of 2 rows stacked. 5 of those tiles will be pink, 1 will be red. 2nd wall will be pink. 3rd wall will be purple. Ive played with all the materials specified, and made them all flat colours of their assigned names. It appears some arent used, or ignored.