Besides the GCW0, I also have the RG350 from Anbernic so I'll try it myself and see if it works correctly.
UPDATE: Just tried. RG350 displays the colors wrong. I see now maybe the SDL port on RG350 does not convert correctly from 8bpp palletized to 16bit? I could try on dingoonity forum and ask the devs (not sure if it's an issue of opendingux or the rogue firmware I used on my RG350).
Even more funny, it does actually work nicely on GameKiddy 350h. GKD can run OPKs from GCW0/RG350 but is less compatible than both of this (other emuls just fail sometimes), I wasn't even initially expecting to run it there, but I guess their SDL implementation was more correct.