Is there a way to make the triggers on an XInput controller act as buttons in PSO2?

[the_importer_]

At least for the first part, a mapping software, like JoyToKey, should be able to help you. Just disable the functions of the triggers under controller settings in-game, and through the software assign the keyboard keys that correspond to the function you want to the triggers.

Not familiar with JoyToKey, I use Xpadder, but regardless, won't this cause me the same issue since you can't press 2 keyboard keys at the same time?