hah ) I don't have much insights, only some opinions )
1. Add a short dotted line to show the start of trajectory - this reduces some "trial and error" situations.
2. Make sure that colliders are consistent and bounce the ball like you predict it does on every point
3. Maybe reduce max speed of the ball - sometimes I lose, not knowing how (and sometimes win - it feels even worse :)
But this is just opinions! You know your game much better than me )