While good attempt in 2012, afaik we can do better these days with e.g. ok* family of colorspaces: https://bottosson.github.io/posts/colorpicker/ (includes section on hsluv)
Let's say you develop a luxury theme, the yellow - purple opponency would naturally lead you to the classic colors of royality, purple and gold.
A good RYB based picker is the good old Paletton: https://paletton.com/
I am also very dubious about the claim of the color pairings being more or less "culturally relevant".
RYB is more culturally relevant because artists and designers "produce" culture based on it.
I think this is a stretch, red and blue are also classic colours of royalty.