I think your mod is pretty good, all in all, but nevertheless I have a suggestion and a question/bug to report...
First the suggestion, it's just about a little detail, would you think about adding the Dome of Stars (in Osgiliath) to the list of unique building, pictures you can find easily, and I think it's quite reallistc that it could be rebuild, and it's easy for you to add into the game, too.
The other problem is, that while my Reunited Kingdom-campaign it occured, that I couldn't build "Culture-Conversion-Buildings" (Librarys, Schools, etc), furthermore if a city grows you can't build the next level of wall, so your cities can not develop.
I tested Rohan and Dale too they couldn't upgrade their walls either, and couldn't build "Culture-Conversion-Buildings" (tombs, ...). The High-Elves and Dwarves worked fine (could upgade cities, and build artist/brewery).
Another thing is that Mordor does not get destroyed, when the Ring is destroyed, nor does it later in the game, amusingly the Ring gets found one turn after he has been destroyed, by an general of the OotMM ;-)
Last Point: maybe the Beorning-Faction gets destroyed too easily, but apart from that the mod works quite well