When 'guifontwide' is set, bold or italic fonts are not used for
wide characters even they are selected by syntax highlighting.
I and Taro MURAOKA wrote a patch for that. Please apply Taro's
correct-ifdef-indent.diff(*) before this patch.
(*) https://groups.google.com/d/msg/vim_dev/D4mMcMFP7ak/N-Yy8y3lpLwJ
Note that this patch only fixes the problem on Windows.
We wrote a comment for other OSes in the patch.
Best regards,
Ken Takata