Once I set it up, the actual shots, angles, and speed is easier to see and my idea does not work in the real world because the balls are a few inches out of position. There is too much angle on the 2 ball shot to draw the cueball past the 7 with any control. the 4 is too thin of a cut to slow the cueball with precision.
So, what I ended up with is - I can play the 9 two ways, both equally successful I would estimate at 70% - 90%. I can play it your way, rolling forward off the 10 and shooting it in the lower side, or I can draw the cueball straight back from the 12 into the rail and off, and cut the 9 in the other side. The first way the 10 is the harder shot, the other way the 9. Straight back draw shots when the cueball is close to the object ball are amazingly controllable, and a shot like this is an often overlooked position play.
The 8 ball I could just stop on the 12 and make the 8 in the side. It would be a pretty high percentage for me on a table with 5" sides. Mine is tight at 4.5" and i made it most of the time. I set the 8 up on the diamond you showed and it was pretty easy. It was easier on the table than it looks in the diagram for some reason, at least I hope I set it up right.
The 7 ball I played as you did, rolling forward on the 12 and shooting it in the corner. Again, the shot had less angle in real life than it looked like on the diagram. I did not freeze the 7 to the rail and I made it 8 of 10. I always had a shot at it and when I missed it was undercut both times. If the 7 were frozen to the rail, then you would have a percentage shot that would separate some. Some people are good at these and others are not.
Chris