I don't quite understand "Language pack service pack". My environment is running with SP2013 standard with simplified and traditional Chinese language pack installed.
When I try to download the SP for language pack: http://www.microsoft.com/zh-tw/download/details.aspx?id=42004
I found it also have different language version. So I need to download all 3 language packs (Engish, and two Chinese) sp and install them on all server instance in the farm?