The machine also said he never rolls a bad roll. Based on that, I reason that it must choose the best nen ability for the task - along with the limitation that would make it "troublesome".
-Shoot raging ant in the head, but you have one second.
-Eliminate all ants in the area, might kill your friends.
Besides being troublesome though, I wonder how it uses up Kite's nen? Is it the summon, or the attack? For example, if Kite was low on reserves, will he be:
-unable to summon the gun?
-unable to maintain the summon of the gun?
-unable to fire the gun?