I can care less for Galaxies, I never even considered thay had a name or required one. Naming sectors is simply beyond my understanding - you can name them whatever you like in your Navigation Registry, while sectors with stations by default are represented by the name of the said station.
But the ability for renaming Stars is the absolute must. Names that they are given at the moment are just ridiculous and inpractical - half of them arent build for human vocalization, while others are the same for hundreds of other stars. Renaming planets is also a good thing, although I'd personally would be just fine with them inheriting the name of the Star with a corresponding celestial order signatures (Prime, II, IV, etc.) based on their orbit. Starting with that, and then being able to give them a specific name for the cake of lore and better identity within and outside of a Faction will be the absolute best!