Thank you dop2000 for your help
Your workaround is very interesting, but to me the biggest hurdle (in addition to the one you already mentioned) is that it doesn't work at all with the second trigger : the "On any button released". Because of the lack of appropriate property in the Gamepad object.
Even if I get rid of the triggers altogether like you suggest in your last part it's still very complicated.
I'm trying to think of something but I feel like I'd have to track the state of each button at every frame, as well as their previous state from the last frame, to see if a button has changed state etc etc... that sounds like a loooot of work. And a looooot of variables to store all these data.
Or if I manage to know when several buttons are released, I could store the IDs of these buttons in a Text variable, separated with "/".
I'd use the tokenat function to split the variable later.
It's almost like building a virtual controller from scratch... Am I the only one to find it incredibly impractical ?
What surprises me is that it looks like a pretty basic fonctionnality... I mean, it's common to mash several buttons at the same time. This trigger is almost useless, limited as it is
Maybe I'm just watching it the wrong way.