I am working on a setting that, in part, chronicles the history of a space faring civilization. The early parts of this chronicle is also an alternate history that is analogous to our own history. For example there was a great civilization that ruled over much of Europe that is analogous to the Roman Empire. Or a major global conflict at the end of the industrial age that is analogous to World War One.
The issue I am having is reconciling this alternate history with names used in our own world. For instance, in my world people living in England would be culturally similar to the English of our world. However, as this is an alternate history, they would not refer to themselves as English. This means that if I described a colony on another planet that was settled by the English I could not simply say Colony of ____ was established by the people of England. Instead I would have to say something like the Colony of ____ was established by people of ____ Isles off the coast of mainland ____. To an audience the latter doesn't convey much meaning.
This wouldn't be much of an issue if this was the only colony, however, my setting contains MANY different locations all of which have some connection back to Earth and Earth cultures. Additionally it's harder to hint at a colony's culture with names alone. I can't hint at New Tokyo being a Japanese colony because old Tokyo itself would have a different name. Instead I would have to add redundant descriptions just to explain something that could normally be done with a single word.
Is there a way I can use alternate history names without needy lengthy descriptions or a an appendix of ____ = England, ____ = Japan? Or should I just give in and use real world names because this current setup is too complicated to be worthwhile?
As some extra context, I am currently not writing a story. This project is currently in a worldbuilding phase and I intend to use it as a setting for multiple stories. The naming issue is something I foresee as being a major problem so I'd like to solve it sooner rather than later.