After seeing discussions of Nedic and Colovian Imperials, I did some Googling to bring myself up to speed but a lot was unclear. Please correct me if any of this is incorrect or if I’ve missed anything important!
The Imperial region consisted of mostly Nedes in the east and Colovians in the west. The Colovians are descended primarily from Nords and retain a number of aspects of their culture. The Nedes are descended from ancient Nedic tribes (as to my understanding are the Bretons and Reachmen), have a sophisticated culture, and were known as diplomats and traders.
What I think of as the Imperial culture seems to be primarily Nedic then? And the Romanesque names? This was most difficult for me to find information on, what comprise Nedic or Colovian names.
This describes the fundamental differences between Nibenay and Colovia, although it's written from a time(line) in which Cyrodiil was tropical. I'd also recommend taking anything there about the origins of Cyrodiilic people with a pinch of salt; it was politically expedient to play up mankind's connections to Skyrim and Atmora.
There doesn't seem to be a big difference in naming conventions between Colovians and Nibenese by the second era (eso's timeframe).
Here's some examples of Colovians: https://en.uesp.net/wiki/Online:Legion_of_the_West_Weald
And some Nibenese: https://en.uesp.net/wiki/Online:Euraxians
If you wanted proper ancient Nedic names, you could look at some of the Craglorn stuff, like the various Skyreach locales, or Shada's Tear. Stuff like Kestic and Kuamac, but I don't know if there's any sort of established naming conventions really. Maybe lots of hard K and C sounds?
Thank you all for the information! I see that a large part of my confusion was from conflating Nedes with Nedic!
Now I need to find the right Nedic name and then I will create my Imperial character!