That may be a valid point, but I never aim in the conventional sense so it would be hard to check. In fact, even ghost ball messes me up. I look at the pocket, the OB, see the shot line and try to get down on it correctly (that's where I blow it I suspect). After that I only see the OB as the intersection of two lines, kinda like the pin in a door hinge. I focus on those lines and try to hit the CB exactly where i want to hit it (I'm pretty sure I look at it last). I have no idea how this works. There may be better ways, but I never learned them and now they'd only confuse me. Feel works best for me, but I won't malign others who believe in and use aiming systems. It's only a freaking game after all.
The whole idea of using the diamond to aim at is that it is a physical point that I can sight, not like a contact point on the OB. From my perspective, I hit it dead on. I should have close to half an inch of CB deflection (yes, CJ, I hate "squirt", but everybody uses it here) over that distance. Seems I'd see that pretty easily.
Besides, I have done that MOFU-whatever drill hundreds of times. Left, right or center ball hit, I always hit the center diamond on the foot rail without consciously adjusting for squirt. I'm sure I do it, but I don't know how or when I do it.
The human brain is simply amazing, eh?