The original depiction of Kai and his Zeta era depiction and finally the side stories is better than origin, considering he actually evolve his character and become a stalwart allies and the UC Equivalent of James Bond / Special Agent !
Kai still reached the 65% mark of awakened Newtype potential, that's why he was able to have Newtype flashes in the closing clashes during in December of 079. Same with Sayla. Eight years later, during the Gryps conflict, both might have risen to match Lalah's pre-death 70% Awakening.