I think they are based on an early VGA design from Tsenglabs, I believe 16bit at 800x600 is the max. If memory serves me well they have a 8bit, 12bit and 16bit but some weird way to address 24bit colour locations.
It is a weird card with 2 levels of hardware fixes required because the designer never got to finish the design before it was pushed into production

Another wasted Amiga opportunity.
If you can, buy a Picasso 2+ or the GVP Spectrum.
I have an A3000 with the GVP Spectrum and it has been great, faultless operation for many years with auto monitor switching on a nice 17inch CRT display.
Az