EDIT: Also, it looks like the trigger numbers just stem from the default TGE code. 1 is alt fire.
AHHHH okay I see that makes sense now. By default alt-fire is jump-jet (im pretty sure?) but since that isn't needed for a combine trigger/separate lone key that does both (BL uses 2 triggers, right click and space) I imagine the alt fire trigger isn't used for anything and it is commented out....unless a weapon state uses it specifically? Still not 100% on this.
Ok so the thing is that the key should be 'sticky', like onTriggerUp or onTriggerDown, so that when you hold the button it crouch but when you lift up it stops. I'm not sure it possible with cmd server commands. is it?
I could see how running out of triggers could hurt you here if you specifically need "sticky" keys as you call it (registers press and release). One option could be making the sprint trigger a toggle type system (press numpad 5 to toggle sprinting, press again to toggle walking) so you can use shift for something else - you could apply this to crouching instead since it seems a bit more practical to toggle between crouching and standing with 2 keypresses instead of sprinting
