Looking good, GP. I had not heard of Nendo before but it looks like a great little 3d programme. I'm in complete agreement with your frustration about town maps suffering because the roofs are usually pretty boring and it's hard (I think shadows are the only way to do it) to emphasise varying heights - hence the decision in Stormlit Cloister map to get rid of the roofs altogether.
I briefly flirted with the idea of an isometric view, but then got very scared when I saw how much work and artistic ability was involved!
Which CWBP map is Castle Darkrovia in?