They already made it clear that with a sufficiently high level stone, one didn't need to know the intricacies and minute details of the item they were crafting, and the world magic would fill in the gaps based on the intent of the user.
Still, a joystick is about the worst interface for bipedal robotic armor. Armored Core uses direct neural interface, G Gundam uses a bodysuit. Knights and Magic uses magic programming, likely similar to this, and levers to actuate these programs for walking, running, avoiding impediments and hazards.