Thanks. Now I understand it should be a tempalte vendor's problem, they customize the font picker so it includes Japanese but not Chinese.
By the way, since we are already talking about font picker, how do I set two different fonts (one as fallback) with Font Picker? I read the doc but I don't think it mentions this. What I want to achieve is style like
font-family: "Open Sans", "Microsoft Yahei"
I fill in the blank
family=Open+Sans:700,400,400italic, "Microsoft Yahei"
But it doesn't work. It comes out the compiled CSS only shows
font-familiy: "Open Sans"