I was looking at your post and decided to look at your district website. Here is what I noticed. You said:
However she missed the d54 cutoff very slightly when her WISC scores came - 124 in verbal and 133 in perceptual.
The website states: Students must score a minimum of 134 on the verbal
AND a 133 on the perceptual to be eligible for this program. (Emphasis mine)
You may not want to hear this but all of the qualifications you listed that she had are MINIMUM requirements for the district magnet. The WISC is the most reliable measure you listed but you hope you can discount that one as less important. A standard deviation on the WISC would be 15 points.
Your daughter's score for perceptual at 133 is the minimum score to qualify but her verbal is 10 points below this minimum which is close to an entire standard deviation below. Unless she had some substantial issue during testing or has a learning disability that affects the accuracy of her tests then she is unlikely to ever score that minimum of 10 points higher no matter how often you test her. That isn't a tiny miss.
I think at this point your best solution is to accept that your daughter is very intelligent and will do well in the gifted program outside of the magnet. Over at the magnet they are more likely to have kids a standard deviation (or more) above your daughter.
Your district is very blessed to offer options at many levels of giftedness but it doesn't mean that every gifted child needs the same instruction. Your daughter will likely be in the top of the group, make good grades, and be very successful outside of magnet in her local gifted class.
You probably didn't want this advice and you are free to do with it what you want but my honest reaction is that if you read a bit more on this discussion board you will see what a tremendous difference there is in levels of giftedness with kids with WISC FSIQs in the 140s, 150s, 160s, 170s, and even 180s+. There needs to be a place for them to learn too. KWIM?