How do I handle real and invented place names in an alternate Roman-inspired Empire?

I'm developing the world for a fantasy novel (or at least trying it) set in an alternate version of Europe, where the Roman Empire didn’t fall as in our history. In this timeline, Gaul and Hispania become the main inheritors of Roman legacy, forming a new feudal Empire—something between the Byzantine Empire and the Holy Roman Empire—with added elements like magic, new religions, and races like elves and dwarfs.

My issue is with naming cities and regions. I’d like the Empire to include:

Cities with real or historical names (like Cordoba, Paris, Lisbon) in Latin, because they bring familiarity, cultural weight, and historical context.

Invented cities with a more fantastic (like in whatever fantastic world, like King's Landing, Winterfell, Dragon stone..), representing magical or noble-founded places that maybe emerged later.

But this mix bothers me. Sometimes it feels like it breaks the internal coherence of the world, or just the mix don't sound good. I’m unsure whether to:

Use only invented names inspired by historical ones

Keep some real names but rename or evolve them slightly

Justify the coexistence as something deliberate in-world

Some context: Celtic culture still remaining somehow and have change the Empire, also the empire is just formed by humans. Although they call themselves "Rome" they doesn't act like Roman Empire anymore. The history takes like in 1000 a.C.

Has anyone faced something similar in their worldbuilding? How do you balance recognizable names with invented ones in your setting? Any advice, examples, or thoughts would be greatly appreciated.