1) The default is -63 which means the attack is around here and works for most areas:
2) Now some maps you'll see that the bot might be misclicking the target because it's spread out too far:
In this case we need to increase the -63 to perhaps -83 so it can click a little further left to hit the ship. Try and experiment to see what works best for you.
3) Finally the bot might click a little too far out and we need to get close to the right:
In this case we would decrease the offset from -63 to perhaps -43
This explains the attack offset