Thanks, Kita. Btw, Dromikaites will rectify this situation until next week sunday (or so) - perhaps he's already contacted you. He'll implement the tentative building roster in the edb to get a running beta campaign map (which of course will need a lot of polishing later).
Btw, the file you were looking for (defining wall ownership) is most likely:

For campaign map models:
- data/descr_cultures.txt
- data/descr_sm_settlements.txt

and for the buildings and stats used in battle:
- data/descr_building_battle/dbb_walls_greek.txt (for example) for the stats. In this file, please ready my annotations. They are about 2 years old, but still describe what I originally did to the walls. Be very careful when you edit things here.
- these files (dbb_walls_greek.txt for example) are referenced to towards the end in data/descr_building_battle.txt, and (perhaps) data/descr_items.txt, btw.
- data/descr_walls.txt

...I hope I didn't miss anything.