Machine gunners clear jams all the time, overheating is just one factor. If the breech is exposed to manipulations air crew would be trained to do it themselves, otherwise they wouldn’t expose the breech face at all.
Machine gunners and plane gunners have more proper access to manipulate the guns they are handling
most plane cockpits with direct gun access only allow the pilot to clear and cock the gun while in the air at best
this does not take into account that maybe the barrel or the breech were damaged by overheating and could cause a catastrophic failure
OP mentions A6Ms as example

how would you clear and shoot again a heat damaged breech or barrel there?
sure you can try cocking the gun but you might risk it blowing on your face
For MG151
push a button to clear the loaded round → OOPS your overheated gun malfunctioned and made the barrel be obstructed → try to shoot it → best case scenario the gun becomes unusable
worst case, it blows up and takes a chunk of your plane
you seem to forget what heat and soot can do to guns
and thats just a small arms example with breaks in between reloads and in a cold enviroment
imagine trying to do that with continuous fire on a 20mm cannon, yeah if it stops shooting i wouldnt even try to unjam it mid flight
TL;DR: if you dont want to deal with overheating learn how to let go of the trigger
I don’t have a problem with holding trigger for more than 5 seconds. I don’t even know how long it takes to jam guns in this game because I never face the issue.
Depends on the weapon.
Most planes don’t. You’re looking at specific examples with nose-mounted guns that are exposed to the pilot. However, most planes didn’t have this. Some planes did have a button that could attempt to reset the cycling by rejecting the casing that failed to eject however this wasn’t always the case. Some planes such as P-47s, Mustangs(Depending on the variant/model), Spitfires, and Hurricanes didn’t have such features. Till later on and that’s if they did or not.
As long as its historically possible. Though depending on the method done to clear the jam there should be some RNG connected to your crew skill in the Weapon Maintenance department. For things like the A6M’s internal mgs is should be basically a 95% clear chance but if its for some sort of cannon clear system then there should be more of a chance of a full failure.
so technically, according to
there should be a time limit before they “cool down” and can be used again?
No, they jam because they were overheated.
Once jamed you need ground crews to unjam them.
Cooling down only prevents to happen jams in the first place.
Some guns could be unjamed in flight, electrically or pneumatically, but that was mostly to clear missfires.
Sometimes it could clear other jams, but if a gun jamed from overheating, the malfunction generally couldn’t be cleared by simply pulling the charging handle.
Some closed bolt guns, like US .50cals, could have their ammunition cook-off from getting to hot, firing until they eventually jam.
A lot of guns have a de-jam sistem so why not +1.