i just figured that the regular names used by Sunfolk and Go Backs were their soul names. Wolfriders take on superficial "tribe" names to protect their inner selves-- in part because of culture. They are always described as being 'shy' and private. Sunfolk don't really send much- neither do Go Backs, and they might not care anyway. Gliders may not have had any sense of privacy, living as they did as a collective... unless they were Winnowil. Or maybe, being more advanced in some ways, they didn't need the crutch of a soul name to shield their "innermost" thoughts.
Of all the non-wolfrider tribes, I would guess that the Wavedancers would be most likely to have developed soul names. They are private in a similar way- and reserved. And they send all the time! It rather seems as if some Wavedancers use non-soul names to identify themselves (like Snakeskin) and others simply use their true names (like Brill, perhaps). Maybe this has to do with them being very close to high ones, but continuing to evolve. Maybe in a few more generations, they would all have had soul names and tribe names... just like the Wolfriders.
It's possible that the Wolfriders evolved and changed faster than the other elves due to a shorter lifespan and faster generational turn-over.
those are my thoughts.