In
this PDF (zhspacing for XeTeX) it seems grid typesetting is simply ignored (see the bottom of page 4). It says it's "proper typesetting" and it's written by a Chinese (or so it seems), but of course, I can't comment on the validity of this.
Then, according to
this page:
There are no spaces between words in typeset Chinese, and all characters are as wide, including punctuation, brackets etc. A word consisting of several characters may be divided at any point, so a column in Chinese is naturally justified at both edges. It often happens that a punctuation character drops alone to the beginning of a line, which looks bad. This can be corrected by increasing the character spacing of the previous line, or by re-formulating the language.