You dont need for touch register setup (maybe controller IC have one but simpler way is)
edit in target file TouchGFX\target\STM32TouchController.cpp
bool STM32TouchController::sampleTouch(int32_t& x, int32_t& y)
{
/**
* By default sampleTouch returns false,
* return true if a touch has been detected, otherwise false.
*
* Coordinates are passed to the caller by reference by x and y.
*
* This function is called by the TouchGFX framework.
* By default sampleTouch is called every tick, this can be adjusted by HAL::setTouchSampleRate(int8_t);
*
*/
if(i2cRXbuff[0]==0) return false;
x=i2cRXbuff[2];
y=i2cRXbuff[4];
return true;
}
This is only example code and for change flip simply rewrite two lines x=XMAX-x; ...