You have "Wait 7 seconds" inside of "Every random() seconds" loop, this can cause all kinds of problems..
You basically start lots of delayed "set bombSkill=0" actions. When you press Q the second time, some of those delayed actions may still be running, that's why your bombing stops early.
Try not to use long running "Waits" for tasks like this, use Timer behavior instead.
On Q pressed
skillSpawn start Timer "StopBombing" for 7 seconds
Every random(02, 04) seconds -> Spawn bombs
skillSpawn On Timer "StopBombing"