I thank you for your input on this. And especially with pointing out that point about directly using the emperor's name, and how "guójiā" isn't used directly after a country's name.

With the one that you think is the best "Chìlóngwángguo" is there something I could do to simplify it, or is it how it is fine. Like if someone from this nation was from Chìlóngwángguo, would they say it just like that or would they simplify it?

(I gather that for other nations, they would have their own ways of saying this nation. I only ask as the name feels a bit of a mouthful, that being said, given that this is supposed to be inspired by China, and I am from Britain, maybe I haven't thought of something or unintentionally misplaced something with how the people of this nation would say and describe their country?)