Ah, I just happen to be wondering the exact same thing. I have received a couple of those 480x320 panels with an ILI9486 controller, and from the DS, I got the same thing as you did, but I've also seen source code that would still use 16bpp data using SPI. I guess those libs are all bogus?
Have you finally gotten this to work, and if so, what format did you use?