I think this might be a hardcode issue but I wanna make sure, is there a property or some kind of way around to make infantry able to shot while jumping the same way a jet trooper can?

One thing could be making all units hover type so I just give them a slight boost for them to shot with some timing, but it would be rather "unnatural" if the unit has no jet pack at all (graphically speaking of course), so I am looking for an answer before I rely on my last option.

i think, im not entirely sure but i believe thats one of those hardcoded things. obviosully u can do a jetpack but if you mean jump up and shoot while a unit reaches theyre maximum altitude or something like that, i dont think its possible. the only time ive seen it happen is in a glitch in 1st person, when u jump it seems to start shooting as you fall down lol...
(you prbly never got a reply cause idk if anyone knows the true 100% truth answer...)

No one can shoot while jumping, not jettroopers, not anyone. In the "jump" state it simply can't be done. In the "jet" state it can be done (which is how it works for jet troopers and dark troopers) and it can work in a fall (which is essentially the same as "stand").

I didn't get that last part (translation loss maybe), for the most part I was wondering if there could be some "fragment" of the jet state I could call for normal units to go on jet state while jumping, but it looks like I'll need to go for making all hover soldiers with something like a half second small boost for it to improve gameplay; then if there is no other suggestion I have only one thing to confirm, if I tamper with collision scale even a jet trooper can take fall damage, right?

Sure, there's nothing special about jettroopers. The only difference is that CollisionScale line in their .odfs.

And that last part in my previous reply explained how shooting in midair works. You can't jump off of something and be able to shoot (notice you'll be in the jumping animation). However, if you just walk off a ledge, you'll be able to shoot no problem, because you never "jumped" and consequently never entered the "jump" state which makes it so you can't shoot.

Thanks, once I finish my experiment it might give some good results to FAQ it, I hope...