12 appears to be the missing one.
The 4/12 color seams more distinctly purplish than in the reference pic.
Oops, forgot to mark the 3.
It looks to me like too much of the sphere is white for it to be any high-number ball.
I think you have the 15 and 7 swapped. And whether the 12 is a 12 or an extra cue ball is still an open question.
Yup, you're right.
>I personally don't see any significance in the rack or the order of the balls
Agreed. It looks like they were just thrown in randomly.
But logically must be a 12 look like it shows a little too much of the sphere being white. It could be a 12. But if it's not then that'd be just the like of hint that Q+ likes to drop.
*But what logically