Pre-training Saitama has superhuman speed because he dodged and slipped over Crablante before he could react. Since Crablante is a tiger level threat, it's fair to assume he has superhuman speed. However, In-training Saitama is calced at supersonic. Remember, this is the Saitama who got blindsided by a tiger level threat "Personification of a Pull-Light Cord" that Zombieman should be at least somewhat superior to. Therefore, the new scaling chain for homeless emperor chain should be...
Intraining Saitama (Supersonic) =~ Personification of a Pull Light Cord (Supersonic) < Zombieman (at least Supersonic)=~ Homeless Emperor (at least supersonic physically, MHS with orbs).
Also, Personification of a Pull Light Cord should be supersonic instead of superhuman, he was able to react to a supersonic Saitama in chapter 15.5 of the manga while he was speeding towards him (He was turning his head before Saitama was interrupted by a pang of pain).
Homeless Emperor might be a little slower than Zombieman since he had to have a heads-up from Zombieman to react to his axe slash from behind, but HE needs to be comparable in speed physically (at least supersonic) to dodge the swing in time.