Yes. They could be used to Dx dyslexia/dysgraphia. The discrepancy approach could be used for that. Or the PSW (pattern of strengths and weaknesses) approach, which was taken into consideration in the design of the WISC-V.
There are nonsense word reading tasks on the KTEA-3, which are supposed to distinguish between good guessing words from context/memorized whole word reading and actual decoding.
Dysgraphia diagnosis does rely heavily on writing samples, timed and otherwise, which the KTEA-3 would obtain, in addition to deficits in other associated skills, such as fine-motor skills/visual-motor integration, motor speed, and strengths/intact skills in areas such as oral language (in order to distinguish from the combined oral and written language disorders).
