No one lied to you before. Its absolutely impossible to allow the renaming of frigates, planetary structures, or anything else that doesn't have an individual name. Your only option is to make them all capialships, starbases or something else which does have a name. In theory you could roughly translate most things in the game to something like this, but the overall effect would be some radical game changes (maw would be broken, unlimited starbases per gravity well etc.), and would be a substantial task for even a somewhat experienced modder.
Now for the devs they might be able to just copy some code and make it work, but we do not have access to anything related to custom names save being able to define the default names themselves.