This is on Mandriva Cooker with evolution 2.22.3:

if [ -f "C/evolution.xml" ]; then d="../"; else d="/home/goetz/svn/evolution/BUILD/evolution-2.22.3/help/"; fi; \
        (cd mk/ && \
          `which xml2po` -e -p \
            "${d}mk/mk.po" \
            "${d}C/evolution.xml" > evolution.xml.tmp && \
            cp evolution.xml.tmp evolution.xml && rm -f evolution.xml.tmp)
C/evolution.xml:153: parser error : AttValue: " or ' expected
  <para>Evolution is a highly evolved<link linkend=\"groupware\">groupware</link
                                                   ^
C/evolution.xml:153: parser error : attributes construct error
  <para>Evolution is a highly evolved<link linkend=\"groupware\">groupware</link
                                                   ^
C/evolution.xml:153: parser error : Couldn't find end of Start Tag link line 153
  <para>Evolution is a highly evolved<link linkend=\"groupware\">groupware</link
                                                   ^
C/evolution.xml:153: parser error : Opening and ending tag mismatch: para line 153 and link
 <para>Evolution is a highly evolved<link linkend=\"groupware\">groupware</link>
                                                                               ^
C/evolution.xml:153: parser error : Opening and ending tag mismatch: chapter line 151 and para
 or on a network and thus handle the daily communication more effectively.</para
                                                                               ^
C/evolution.xml:160: parser error : Opening and ending tag mismatch: book line 14 and itemizedlist
  </itemizedlist>
                 ^
C/evolution.xml:162: parser error : Extra content at the end of the document
  <section id="usage-mainwindow-starting">
  ^
xsltproc -o evolution-C.omf --stringparam db2omf.basename evolution --stringparam db2omf.format 'docbook' --stringparam db2omf.dtd  --stringparam db2omf.lang C --stringparam db2omf.omf_dir "/usr/share/omf" --stringparam db2omf.help_dir "/usr/share/gnome/help" --stringparam db2omf.omf_in "/home/goetz/svn/evolution/BUILD/evolution-2.22.3/help/evolution.omf.in"  --stringparam db2omf.scrollkeeper_cl "`scrollkeeper-config --pkgdatadir`/Templates/C/scrollkeeper_cl.xml" `/usr/bin/pkg-config --variable db2omf gnome-doc-utils` C/evolution.xml || { rm -f "evolution-C.omf"; exit 1; }
warning: failed to load external entity "db2omf.lang"
cannot parse db2omf.lang