I'll try to make my post as compressed as possible as to not confuse people.
"Jinpachi Mishima without being amped by devil has holded part of mountain for 20 years."
There is no reason to believe he was holding the
whole mountain, video itself shows he was holding a big stone/statue, even so this is only an endurance and liftingh strenght feat, not a DC one
"Even Gun Jack can block explosion that destroyed entire forest and extended over mountain range"
We have no way to gauge the size of the mountain range, much less any reason to believe the explosion even reached that far to begin with so you can't say the explosion covered said distance, if anything this looks like a baseline 7-B (city level) feat rather than a 7-A (mountain level) as the mountains didn't seem to recieve noticeable damage in the aftermath
Besides, you need to calculate the actual DC of the feat to begin with, you can't go around assuming the yield of the attack is enough to warrant the ratings.
"Gun Jack can react to blast that came from satellite to ground in a second "
You're forgetting the beam comes from orbit, and unless we see him actually moving, or reacting to the attack when it is
1m away from him we can't scale the beam speed directly to his reactions.
"1. Reaction speed has both a distance and a timeframe component, so all calculations that are completed for reaction speed cannot simply be a timeframe by itself. Do not randomly assume a 1 meter distance for each timeframe and use that speed for the reaction speed."
https://vsbattles.fandom.com/wiki/Reactions
As for scaling in-universe is up to anyone, but bear in mind the gaps in tiers so don't assume that just because 1 character can stomp another it automatically means he is of a higher tier.