Flight Instructor reported a near miss with an aerobatic aircraft while on approach to land and took evasive action to avoid a collision.

Narrative

The situation is regarding the aerobatic pilots in the aerobatic box inside the Columbus; GA class D airspace while towered operations are in effect. The pilot was flying Aircraft Y in the aerobatic box. According to the pilots the box goes down to the surface. When traffic is arriving or departing tower will tell them; 'remain north of the 6/24 centerline.' They tell them but many times venture further and further south. Many times the pilots are not even on the tower frequency. They're getting second hand instructions via their ground monitor so instructions are at least 10 seconds late many times. I was inbound from the practice area with a student on a routine training flight. The aerobatic pilot was in the aerobatic box so ATC gave me directions to enter a wide left base to enter a three mile final in order to avoid the aircraft. As I'm turning final I'm give the clearance to land and ATC once agains informs the aerobatic pilot to remain north of the 6/24 centerline. As I'm on short final about 200' AGL I look up and Aircraft Y is within 300' directly on top of us going the opposite direction and inverted. I grabbed the controls from my student and pushed the nose down to get more distance. I could not go around as that would bring our vertical separation down even more.After the experience I called the tower to complain and was told there isn't much they can do because even though Aircraft Y has a transponder; it's almost never used and thus were not able to provide an accurate picture of vertical separation using their radar. My best estimate was that the pilot in Aircraft Y was somewhere between 200-300' above us at the time of the near midair. We did land as safely as we could and immediately after landing Aircraft Y radioed; 'ok; I'm all done; I'm ready to come down.'There have been a plethora of issues with the local aerobatic pilots in the past but this was the closest they've gotten to me. Many others have had very similar situations as well. The overall outcome was we did land as safely as possible regarding the situation.