This apparent problem has to do with the variables _colstart and _rowstart, which in turn are related to the type and size of TFT: GREENTAB, BLACKTAB, REDTAB and different variants
Perhaps you should test your code with another variant of TFT, which adapts correctly to your screen. If none of them work for you, you could generate your own variant, defining the correct values for _colstart and _rowstart