I've tried unticking the snap to afcad but it still overshoots the centre line.
You cannot just untick the snap setting, and hope something will change. That setting is ONLY used when you create a Custom Pushback and, if Snap mode is off, you'll have to define both the Pushback end point and heading AND the curve corner.
This last one is the one that, when set correctly, will allow to do pushback way more correct and precise and tight than ever before.
We would like to have a tutorial on this but, since we are still planning to update the interface, we would like to wait until it's really finished, so we won't have to redo the tutorial again.