Over at the knee is not a big concern. Mostly it is cosmetic and most would prefer a horse over at the knee than back at the knee.
In a foal, the concern with over at the knee is more with contracted tendons. In this case, the dam is also slightly over at the knee, so it may be that baby inherited that. If most of the blood (75%) is the dam, then you have really increased the chaces of similar conformation.
BTW the dam appears to have a right front fetlock joint injury and ring bone on the outside of that leg just above the hoof. She is also sickle hocked and has a longish coupling.
There is something about the outside of a horse that is good for the inside of a man. ~Winston Churchill
) Dinosaur Horse Trainer