Most of the tests in the W3C Internationalization test suite have now been ported to github at github.com/w3c/i18n-tests/. Follow the links from w3.org/International/tests/ to find test results, then click in the left column of that page to run a test.
W3C is always looking for expert advice on questions related to text layout. Here's what's currently needed for Chinese: w3c.github.io/i18n-activity/… Please contribute to the linked github threads if you have authoritative information.
Just updated: "Inline markup and bidirectional text in HTML" w3.org/blog/International/20… Update brings it in line with recent browser developments and simplifies the guidelines. Examples link to live versions, and browser support information has been added.
Out for review: Updated article, Inline markup and bidirectional text in HTML w3c.github.io/i18n-drafts/ar… . Guidelines simplified, browser support info added, live tests added to examples, etc. Feedback via the link by 12 Dec please.