dev-texlive/texlive-langchinese requires dev-tex/cjk-latex but the ebuild does not list this requirement. Without it, I just get "! LaTeX Error: File `CJKutf8.sty' not found." errors when I try to generate documents containing chinese via \usepackage[UTF8]{ctex}
All cjk stuff have been merged into dev-texlive/texlive-langcjk to follow upstream. In turn texlive-langchinese depends on texlive-langcjk