I was surprised to see that the descriptions and care guide for various species used in bonsai included Chinese quince but not the Japanese quince which appears to be much more widely used for bonsai. I know such information is widely available online and in books, but was wondering why such a popular genus was not included in the Bonsai Empire guide?

I would ask the owner of the site, instead of the forum?

Not sure it matter much, chinese or japanese tbh.