I don't have any knowledge of the technical scoring details on the CogAT, but fwiw, those are great scores and they are strong across all categories. I have no idea if local percentiles are used specifically in your school district, but it sounds like you're in a high-performing school district where there are a large number of higher-ability students - so whether or not local percentiles are used in determining eligibility, the general pool is larger at high percentiles, hence the cut-off bar for program admissions is probably going to be higher than in a not-so-high performing district.
I looked back and saw that your ds has had an IEP for speech disfluency issues, and that you've had concerns with timed tests. The CogAT is a timed test. It would be interesting (if the information still exists) to find out if he ran out of time, and if the questions he missed were questions he actually got incorrect or if they were questions he hadn't attempted to answer yet when the time clock ran out.
If you do think time is an issue for your ds, it might be an issue worth pursuing a request for accommodations - but otoh, to do so you'd need more than just a parent's gut feeling that time is a factor - you'd need assessment and documentation from testing either through the school or a private eval.
Best wishes,
polarbear
