Your kids’ school has MAP test in elementary and IB before graduate high school right? If yes, take MAP as the accurate assessment. Teachers’ comments are their expertise which can be adjusted with your person knowledge of the kid.
My kids only took the ISA ones up to year 10, I think.The following is a sample individual report for ISA science (can't find a sample for English).I find the report quite useful and keep track of their results over the years.