At the moment I don''t have an ILI9341 at hand otherwise I'd try it out.
My current state of modification on the pantata library.
Swapping the colors is easy by just setting MADCTL_RGB, also, the font mirroring is easily corrected by removing MADCTL_MX | , however I'm still having address issues with the library, sometimes it just draws all over the place...but the speed is remarkable!
Wondering whether it's easier to just incorporate the DMA SPI into the Adafruit library after all, because it has better GFX functions. It does work well, but I want more speeeeed with the ATSAMD21, that's why I placed this topic inside this subforum...