the key press function only allows me to bind two keys utilizing the 'Shift, Control, Windows and Alt' key along with one other regular key
Those particular keys are modifiers, I.E. they exist to be combined with another key and don't usually serve a function by themselves in a normal application environment(video games are the exception to that, but computers were not initially designed with those in mind), which is why those are the ones you can combine with others.
If you're looking to press down and release multiple keys near-simultaneously and send them to an application, you can use separate press, pause, and release actions:
Press down W key
Press down S key
Pause 0,01 seconds
Release W key
Release S key
If instead you need to trigger a command using multiple non-modifier keys, you could set the first key as the actual trigger, then follow that up within the command to check if the others are held down:
Begin Text Compare : [{STATE_KEYSTATE:S}] Equals '1'
End Condition - Exit when condition not met
If you press the key almost exactly at the same time(with little margin), those actions will allow the command to run; Otherwise, they stop it before anything else can execute.
There are other ways to accomplish this as well(multiple commands triggered by the individual keys, or loops to check states), but if you're looking to make regular use of such a mechanic, you could put in a
feature request for it.