This is something I was wondering about a while ago.
But I don't think it will go forward, if Gyomei really limited himself to Subsonico, he wouldn't be able to fight
Kokushibo, hence the first inconsistency.
There are several feats to prove the verse above the speed of sound.
Let's take Baki as an example, Yujiro gets blitzed at a speed of 270 km/h, and that doesn't mean we're going to leave him at subsonic level.
Baki takes a lot of damage when falling from a 30 meter drop, but we won't leave him at wall level even for that, even before falling off a cliff and coming out practically intact.
These are inconsistencies that don't make sense with the Power Scale of the work as a whole.