When writing a royal themed fiction story, how accurate should I be?

I think its great you want to create your own country for the story but if you are going to base if off say the African culture I would do some research on African tribes and how they view social hierarchy, royalty, ceremonies, etc. If you are going to go the Hispanic route (which might be easier since I know nothing about Africa except its countries) I would look at the Aztec and Inca civilizations. Even though you are thinking Hispanic it might not hurt to look at the culture of Spain and Portugal as well as North and South America. You might want to also look at some Native American tribes. If you want to be a good writer you should want to have accurate sources. If you just mix cultures off the top of your head than some readers might get offended, like if you mixed all Native American war rituals and then claim they are a tribe in Quebec for the sake of the story. All professional writers, literature, film, plays do a lot of research to make sure the story is coherent.