There is something I appreciate quite a lot in GC3, is that you can rename almost anything, and in particular you can rename planets you don't own and any fleet, even enemy fleets. And why not, this is mostly a SP game, and if it pleases you, what's the injury?
But there is something that bother me. When you rename a star (not a planet) then the hidden name should be changed too, because it is not. It means that a new shipyard or fleet will still bear the old and hidden name. There must be a variable somewhere which is not changed.
To be complete, if you rename a star, it should rename all planets likewise at once, because you are renaming the entire system. It would allow interacting with dead planets names that still can't be changed right now. And if you rename a planet, it means only that. You only rename this planet.
So if I rename a star 'Sol', then all planets are changed to Sol I, Sol II, etc. But if I rename only Sol III to Earth, then only this name is updated.