For me, the most common causes of high right misses would be creeping or not focusing on the target.
If I don't maintain back tension through completion of the shot, I will creep and miss right or high right. As you note, this could be more of a problem with a lighter weight bow, as many people find it harder to get off the string. When I first discovered this problem, I couldn't tell when I was creeping and when I wasn't, so it was helpful to have someone watch me shoot, or to video myself. I finally was able to become aware of when I was creeping, which gave me enough information so I could self-correct this error.
Another cause of high misses can be focusing on the arrow tip rather than on the target. This is also hard to be aware of. But if you miss high, and then really focus on the target on the next shot and don't miss high on that shot, then you can pretty well assume that you were focusing on the arrow tip on the shot you missed. Obviously, this is only a problem for gap shooters, and not for instinctive shooters, who are always focusing on the target.