Having achievement scores two years ahead of where she is does seem to be pretty high academic achievement to me, even if she doesn't show it in ways that you feel look that way. I have read some of your other posts and it seems like you are really trying to understand why these scores might be lower than you expect from her IQ scores. I think the person to ask would be the test administrator.
I think maybe it is more important for your child to encounter something challenging than it is to have really high academic achievement. I also think it is important for a child to be learning *new* things at school.
However, being really challenged is more difficult than it sounds. Especially if your child has a personality where they aren't going to rock the boat... Not being challenged may result in having very poor study skills later on when it counts.
I don't know how often it is the kids have high achievement in early elementary. My thinking is that it is probably not a lot since schools, imo, do not differentiate well at those grades. It will be interesting to hear other views on this.
I'm not sure if this answered your question, but I hope it might help. I am not an expert, and I would be interested in what other parents think.
