Prior Instance of term in main text, before first glo

I am marking up foreign words so that I can display the Japanese/Chinese
characters in my text, but only for only the first usage of a term, and
also to have the stylesheet generate a glossary at the end. Cutting and
pasting and rewriting, it is easy to forget if I have already "glossed" a
term or not, and I cannot figure out a correct xsl test to see if the term
is properly marked up the first time it is used. That is to say, I need to
test to see if the word has been used before (in document order) in the
source tree, before the first glossary markup.

It seems like it should be easy to check with a simple <xsl:if test---> but
I do not seem to be able to get it to work, and I do not see anything
relevant in the archives.

<p>The Buddhist way is zazen. When first practicing sitting meditation
<mygloss><gr>zazen</gr><gk>==Japanese Characters==</gk></mygloss> select a
quiet place. </p>

<xsl:template match="mygloss">
<xsl:if test="contains(ancestor::text(), gr) or contains(preceding::text(), gr)">
       XXX ERROR-- NOT FIRST USAGE XXX
     </xsl:if>
<!----- rest  of template to put in italic, proper font, check for first
gloss markup of this word etc -->
</xsl:template>

This following test works if the word is not further marked up in the
paragraph, but of course it fails to look in end notes and such: