Maybe this is part of the reason you were having trouble with your display mapping properly with the existing subpixel layouts?
It should be possible to retrace my steps with what I did to get the RRBBGGX available in Sony Megatron Colour Video Monitor to find a compatible mask layout for your particular display. All it would take is a little trial and error, to test the various combinations of subpixel colour order until you get one which lines up with your display.