For so called executive functioning and adhd we went this approach. My kids handwriting went from messy to neat in 2 weeks with walking in a figure 8 and juggling balls (just 2). Her transference of looking at a blackboard and writing down on paper was bad. She couldn’t copy a picture correctly. With in weeks it was all fixed. Your situation seems more severe. Biofeedback really helped also more then we would ever think instead of medication. Her room went from messy to neat like overnight.
http://www.ledererandmargolis.com/ ask for referrals to your area. They are like the leads on this therapy they use. In Chicago the doctors and pediatric clinics seem to all refer to them. Maybe a phone consult for direction to go in will be helpful. I have referred many patients kids there with great results including my own kids.