Duckie, it's a little difficult to understand what you're saying. Not sure what the first part of your point is.
With regard to the Cranfield arrow, if you read my booklet you'll find a reference to it in there. I think it's ok but not what I needed so I invented a more simple tool to find that point. It's a combination of the Cranfield arrow and the magic rack. It's printed on a thin piece of plastic so it will not affect the travel of the balls.
You place it under the object ball and move it to the correct alignment to show where the aimpoint is.
Cool.......Now just add the aiming arc to it as in the drawing. The Aiming Arc is the line the ghostball contact patch will move along when the Ghost Ball is moved around the OB while in contact with the OB. It will always 1/2 the diameter of the CB from the outer most edge of the OB.
Another thing that is key is understanding is the OB direction of travel line. It has three points. They are start, pivot and end point. Start point is at the Ghost ball contact patch, the pivot at the OB contact patch and the end point which is where ever you want the OB to go.
Moving the GB contact patch, also the start point for the OB direction of travel, along the Aiming Arc, the OB direction of travel line pivots at the OB, moving the OB direction of travel line end point some distance.
The only time the OB Direction of travel line end point and OB direction of travel start point, also the GB contact patch, will move the same amount is when the OB direction of travel end point is 1/2 the diameter of the CB from the outer most edge of the OB.
When the OB direction of travel line end point is far from the OB, a little change along the Aiming Arc will move the OB direction of travel end point alot more. The amount depends on the distance from the OB direction of travel end point is from the OB contact patch, also the OB direction of travel pivot point.
I use Ghost Ball contact patch. This way my eyes are are always looking at where I want to put the CB. The OB contact point and the GB contact patch are on the same line to where ever you are sending the OB.
The difference is that the contact point of the OB is higher up on the plane of the line, but it its also offset to one side of the CB direction of travel.
For a straight in shot, not a issue, but get close to a 90 degree cut, the the OB contact point is way offset from the CB direction of travel.
And there are no real references points to use. It is all trail and error. It is the visual input from seeing where the CB hits the OB and where the OB goes after that is working. Once you see the correct shot picture, it is in your visual database for future reference.
Ever try a hard shot, then you do it once, then the next time its easier and the next easier and so on. The above is why.
And FWIW, I have never needed to correct for CIT. Spin yes, CIT no.