Asana treats an approval task marked “Changes Requested” as a complete task–it disappears from your “incomplete tasks” list like any other tasks, even though the approval (or disapproval) is not complete. It’s not complete. Changes were requested. There is still work to do before this gets check off the list.
As is, all the approval box really seems to do is let you complete tasks, but with a different color. That’s not very useful.