Hi,
  I wrote a patch to fix the contains comparison for string and langset vars.
Now I can write the match rule like:
   <test name="family" compare="contains">
       <string>Song</string>
   </test>

which will match all families like ZYSong and SongTi, etc.

And the contains comparison for langset is ok now, eg.:
    <test name="lang" compare="contains">
        <string>zh-cn</string>
    </test>

which will match all fonts with zh-cn langset.