Your definition of endurance is actually the definition of stamina, they are very very similar so I suppose that doesn't really matter. However your durability definition is blatantly wrong, I'll elaborate below.
The attack was very very weak. The fact that Charla survived it means that its a dud of a feat. Charla doesn't get the same plot immunity (especially in her fighting mode) as Happy (since she has not shown
any of the "impossibility" that Happy has) does so anything on her is fair game.
Anyone can "tank" an attack that only hits their arm. Look at the area that was hit by Jupiter, its covered in blood. I'll remind you what durability means:
du·ra·bil·i·ty
ˌd(y)o͝orəˈbilədē/
noun
- the ability to withstand wear, pressure, or damage.
Makarov did not withstand Jupiter because Jupiter clearly damaged the area it hit extensively. Its not how much someone can sustain after being hit, its how much someone can sustain
during the course of action. What you are referring to is endurance;
en·dur·ance
inˈd(y)o͝orəns,enˈd(y)o͝orəns/
noun
- the fact or power of enduring an unpleasant or difficult process or situation without giving way
But like I said, anyone can endure an attack to the forearm. Frankly characters should be able to endure through downright having their arm cut off, it doesn't even take a superhuman to do that, especially one on a mission.