Something is not right.
My Coal trol is right next to my Honeywell digital thermostat and they are never more than 1 degree different. I never have more than 1 degree overshoot. My settings are 5Min and 38 Max on a channing III.
Your Min and Max settings should not have anything to do with overshoot. The low setting just keeps the fire from going out and the Max setting keeps hot coals from falling into the ash pan. Thus getting the most BTU's possible from the stove. The Coal trol should see that it is getting near the temp you have set and start slowing the feed rate down.
My Heat loss settings (HLF)are 0. if yours are set higher, this may be the sorce of the problem.