I was looking around for the config_user file and couldn't find it in newer gaomon driver versions so i eventually uses sysinternals process monitor to find where the driver was writing to when i was calibration and i found
C:\Users\[yourusername]\AppData\Roaming\GAOMON\data\EKeySetting.dt was the file that contained the calibration data in newer driver versions
you will find the calibration data under ""CalibrateParam":[66282,1687,-33379612,-178,65592,-926506,65536]" and can search for this with your text editors find text function
this grid made by someone on reddit ages ago who i have forgotton the username of should help with calibrating that: https://imgur.com/99natFs
Factor 0 is the first number (66282) and it goes from there with the second number being factor 1 and the third number being factor 2 and so on
this is likely applicable to huion tablet users as well since huion and gaomon are the same company and seem to follow similar driver structures for both huion and gaomon drivers but folder paths for huion would be obviously slightly different