There are problems with republics in the current release. I've made a lot of changes since then, so hopefully such issues are fixed.
Good; I look forward to playing as Toph's family and founding a clan of warrior-traders.
That is a really good suggestion, and something I will look into fixing after this update.
UPDATE: Simple enough fix. I've changed the code now so that everyone uses Indian CoA's instead of the default Christian ones. Still vanilla, but the Indian CoA's are more in line with the Avatar universe than the Christian ones of course.
On thinking more about the dynasty shields, I agree that the Indian Shields are a good choice.
However I also think that the Tengri Shields (Fire, Torches, War Horses, Swords, Wolves, Eagles), the Generic Pagan Shields (Trees, Longboats, Battle Axes), and the Zoroastrian Shields (Torches, Fire, Dragons) would fit thematically with the setting as well. If it is possible then combining the different shield themes would be a good choice. If that is not possible then I suggest using the Tengri Shields for the Fire Nation, the Generic Pagan Shields for the Water Tribes, and the Indian Shields for the Air Nomads and the Earth Kingdoms.