A critical comparison of Shotokan kata with those of related Okinawan arts reveals that someone has inserted jumps in our katas in places where they don't belong.
The jumps in Heian Godan and Empi were not there originally. They were added to make the katas more dramatic. That's fine for the kata dancers, but the karate-jutsu people need to recognize that the dramatic insertions are also dramatic digressions.
We don't have to explain situations where the performer's feet leave the ground. They aren't real. They are just dance moves.