I feel your frustration!
Our district also uses both the CogAT and MAP scores. For the CogAT, our district uses the Local Percentile (Local grade score, they don't report the regular grade percentile) rather than the age percentiles. If the age percentiles were used, DS would easily qualify but he didn't get in because the Local Percentiles were as much as 15 percentiles LOWER!
DS's CogAT Quantitative was at the 97% for age but only 82% for local grade. His Math MAP score was at the 97%national/92%local (only need 85% local MAP) but the LOCAL quantitative CogAT is keeping him out of the advanced math. Never mind that he already knows everything (and more) that they will be teaching next year.