So in your aiming system, the aim point for all cuts between 30 degrees and 90 degrees is 4mm from the CB center? Why would you think the aim point should be the same for all those cuts?
No, up to 30 degrees the aim point is about one mm off center per degree of cut angle.
So a 10 degree cut aim point is 10 mm off center, 17 degree cut is 17 mm off center.
A 30 degree cut is at 28.56 mm (ball edge, of course), so the approximation starts to show some deviation here.
For 30-50 degrees it is ball edge plus 0.8 mm per degree (sorry, I misspoke above), so a 35 degree cut has the aim point 4mm wide of the ball edge, a 45 degree cut 12mm wide of the ball edge.
Beyond 50 degrees I lose my visualization and use equal-opposite aiming.