Well race is a bit too much, though if it is intended then never mind. But soul traits I suspected are intended it is just not much can change them, only essense warping kind of things, even body swaps swap with them. So it felt uncertain if it should work that way. That is why it is good to get some good descriptions formore complex buildings or processes.
I admit it: usually it is not required, you just can do and see but with void cages it is kinda unclear you change stats in certain way, lose things, then get out well average soul. Which even if mechanically is the same as fully erased of most traits, for player it is not resonates of what is happening, nor when I look in build list void cages I just not sure why should I build it and when I build it no way to learn what actually I built and how to work, because most changes happening to occupants are hidden under the hood, they just stay there, and decay from void usually changes stats randomly(Or I assumed so got few of my old prisoner and servant souls gaining out of nothing mesmer and body shaping traits) while void cages remove stats. So thanks for consideration.
P.S. hmm probably could have figured from some idle soul decay that soul traits might be affected too. Well thanks for hearing me out.