I would like to suggest that the tags chinese and japanese (the tag korean does not exist to date) should be treated as synonyms of the tag cjk.
The reason is that this page primarily deals with typesetting and typographic considerations regarding Chinese, Japanese or Korean, and relevant questions virtually always relate to all three languages. Prominent examples are questions regarding the set up of CJK fonts or regarding the typesetting of languages with scripts that use ideographic characters (although Korean rarely uses them, Korean script is still typeset in a way that matches typesetting ideographic characters).
You are welcome to vote for or against this proposal on the relevant sub page.
(Note that you need to have a total answer score of 5 or more on the relevant tag to be able to vote for tag synonyms.)