The origin of a spirit companion’s name can depend on the type of spirit and can arrive from several different possibilities. It could be their original name from when they lived, a human version of their name, or a name they adopted once in spirit form.
In some cases, the spirit companion’s name might originate from a language or communication system inaccessible to humans and impossible for us to understand. Which is why a spirit will choose a name closest to their original name or represents something special to them.