The 20-fix-globaladvance.conf file we have looks like this:

<fontconfig>
<!--
  Some Asian fonts misadvertise themselves as monospaced when
  in fact they are dual-spaced (half and full).  This makes
  FreeType very confused as it forces all widths to match.
  Undo this magic by disabling the width forcing code -->
        <match target="font">
                <test name="family"><string>GulimChe</string></test>
                <edit name="globaladvance"><bool>false</bool></edit>
        </match>

        <match target="font">
                <test name="family"><string>DotumChe</string></test>
                <edit name="globaladvance"><bool>false</bool></edit>
        </match>

        <match target="font">
                <test name="family"><string>BatangChe</string></test>
                <edit name="globaladvance"><bool>false</bool></edit>
        </match>

        <match target="font">
                <test name="family"><string>GungsuhChe</string></test>
                <edit name="globaladvance"><bool>false</bool></edit>
        </match>
</fontconfig>


Looks to me like this should be changed to target="scan" now?

Also Mandriva has a more generic version:

<fontconfig>
	<!--
		Some Asian fonts misadvertise themselves as monospaced when
		in fact they are dual-spaced (half and full).  This makes
		FreeType very confused as it forces all widths to match.
		Undo this magic by disabling the width forcing code
	-->
	<match target="font">
		<test target="pattern" name="lang" compare="contains">
			<string>zh-tw</string>
			<string>zh-cn</string>
			<string>ja</string>
			<string>ko</string>
		</test>
		<edit name="spacing">
			<const>proportional</const>
		</edit>
		<edit name="globaladvance">
			<bool>false</bool>
		</edit>
	</match>
</fontconfig>

Of course that target="pattern" part is quite bogus.  But the idea of matching on languages the font supports has merit.