The Terra Nova is an achievement test, so measures how well your daughter has learned what she's been taught. The WASI measures specific abilities, but not specific information, if that makes sense.
So there's no reason that a high score on one would necessarily mean a high score on another. I personally would interpret those scores as "bright kid who works really hard."
125 is a bit higher than 90th percentile on most IQ tests, so consistent with the levels of participation you're seeing in the school program.
As far as having her privately retested, you might want to consider whether the school would do anything differently if she retested high enough to meet the cutoff. (I don't believe that the district I'm in would - their test is the only one that counts.) If not, is there anything you as parents would do differently if she retested high enough to meet the cutoff?
