I think the buildings will be restricted by culture, but I've only seen four different building sets from vanilla (Northern European, Southern European, Islamic and Aztec), which could be a tad problematic.

According to the current faction list the buildings would be something like this:

Northern European = Bretonnia, Empire, Vampire Counts, Kislev, Skaven, Nurgle, Tzeentch
Southern European = Dwarves, High Elves, Dark Elves, Khorne, Slaanesh
Islamic = Tomb Kings, Lizardmen
Aztec = Orcs

Assuming cultures types can be changed, this is how I would see it:

NE = Bretonnia, Empire, VC, Kislev, Skaven, Dwarves
SE = High Elves
IS = Tomb Kings, Lizardmen
AZ = Orcs, Dark Elves, Khorne, Slaanesh, Nurgle, Tzeentch

Or, if more sets can be used:

NE = Bretonnia, Empire, VC, Kislev, Skaven
SE = High Elves
IS = Tomb Kings, Lizardmen
AZ = Orcs
01 = Dwarves
02 = Dark Elves, Chaos

It's hardly perfect, and I'm sure others could think of better ones, but it's just a thought

I've been trying to edit the building files myself for my mod, but so far all I've been able to edit texture-wise are the overlays like roads and farmland. I think the bulk of the information is in the .world files, so I think someone will need to work on converting/extracting the files into an editable format.