[But it seems like we still don't have the current, official rules!]
I believe there isn't such an official text of rules in any language, anywhere. The PDF files Lee provided is a translation of the proposed 2014 version at the beginning of that year. However, when they published an "official rules" before the master tour stops, a slightly older version was posted, at least they kept the players updated on the rule changes in the player meetings.
They do provide printed English version to the foreign players after their arrival. However, interperation of the rules is still up to the refs in the field. An interpreter is always needed when a dispute occur.
The C8B rules isn't mantained by an formal commitee or a board like the WPA rules. It is only used in the Joy C8B tour. Actually the name C8B is exclusively used by Joy. All other 8 ball events in China are using CBSA rule, which obstinately renamed the 8 ball playing on this type of table as The Chinese Billiards. The CBSA is the government endorsed "governing body" for cue sports in China.
There were quite a few suggestions discussed on the Joy's C8B forum, but not a single feedbacks from the "officials", typos and loopholes are still exist in the latest published rules. So again, there isn't any thing formal and polished like the WPA rules. Chinese are not very serious about rules, period.
The bottom line is, you cannot find a place to buy C8B rule book, you cannot find any authoritive answers anywhere unless you talk to Joy. Even most Joy employees don't know what rules will be in effect in the next event.