Some of the ghost characters do appear to originate from place names, though that doesn't really have anything to do with the addressing system or any postal authority. Of the ones I checked more closely, like 膤, they tend to refer to things that wouldn't necessarily show in an address, like a hill or something.

https://www.wdic.org/w/CUL/%E8%86%A4 https://www.dampfkraft.com/ghost-characters.html