I'm asking if Talos's and the CoC's ascensions to their immortal positions actually made them immortals or not. I'm asking if the CoC actually became a Daedra and if Tiber Septim actually became an Aedra.
Sort of?
They enantinomorphed and mantled. So they became more and less than either one. I think, at least for talos, spirit may be more accurate than "Aedra," since he didn't give a piece of his own body to the world, but Akatosh and shor both did, so he did too without actually doing it. He is a fakeout aedra. as for the CoC, time will tell.
Wierded out yet? I hate sounding like the cryptic bastard, but that's really the only way I know how to tell that story.