Mmm kinda tricky. SPL1 is at 171,192. When you move, it's position stays the same but it appears to move because of the parallax effect. If you move to the right then SPL1 appears to be at, say, 250,192 but to hit it you still need to shoot at 171,192.
So... I created some dummy targets on layer 3 and set their positions to the target's positions taking the parallax into account.
capx