The run-down state of Battanian cities is intentional from a lore perspective - Battania is a declining society which is too poor to build or repair new things and is slowly being conquered by its neighbours. By the time of Warband it has been destroyed completely with not a trace left. That's why all the buildings are collapsing, and why Battania has a cultural downside of slower project construction.
I do agree with
@Brano though, that their cities are slightly too "high fantasy". Dunglanys, Marunath, Seonon and Pen Cannoc are too vertical and over-the-top, built on a mountain with colossally tall stone structures that look like Minas Tirith, which is cool but out of place. Car Banseth, on the other hand, is good, more realistic looking.
Not saying TW should change the existing cities, but when a new city scene is made for either Marunath or Seonon (as they both use the same scene) it would be nice if the last Battanian city looks more realistic, with lower stone structures and built on a hill rather than a mountain. A bit like these: