Well, the pixel mapper does not belong to my part of the software, so I can’t help you much. Take a look here A simple DIY status display with an 8x32 RGB LED - #64 by lubeda. Perhaps you should try rotation: 180 because I think in each block left and right are scrambled.
Here is a tool that may help to find a working pixel_mapper FastLED-XY-Map-Generator
Please, if you find the right pixelmapper post it here.
Thanks