Hey @Hughbacca I still have this same touch scaling problem on a waveshare DSI 7” 1024x600 screen, drives me nuts. The touch drifts further as you go to the bottom right of the screen and touch calibration input goes red but doesn’t progress to the next step. I posted a thread but never found an answer despite the touch input working perfectly when I boot into raspbian desktop.
I also tried adjusting those settings in the 99-calibration.conf without luck. I think the settings may have even existed in two places which made things even more confusing. You reminded me to have another look and I found a few threads on this topic. This one is detailed and has a string for the input matrix that was successful, maybe it could help you? I’m going to try it out when I get a minute.