The D-KEFS can assess multiple aspects of EF, as can the NEPSY-II. The CPT assesses mainly attention, inhibition, and sustained attention. Your evaluator may have used selected subtests from each measure (which definitely is an appropriate use of the instruments), which is giving you the impression that the aspects of EF you list are assessed by those tests.
Your DC's working memory on the WISC-IV would be considered Superior, which suggests that that is not the primary problem. It also looks like, once he caught on to the task (completed the first category), he picked up the remaining categories presented relatively easily, but probably ran out of opportunities. It appears he was administered one of the short forms of the WCST. There is some data that suggests that children who are slow to grasp the task at the beginning tend to have low estimates of ability on the short form, versus the full 20-30 minute form, as their performance improves over the course of the test.
