You can check if a PO file is valid with the following command:

        msgfmt -c -o /dev/null <po file>
      

The following errors were found in glibc 's PO files:

gettext: intl/translit.po: can't guess language
gettext: intl/tstcodeset.po: can't guess language
gettext: intl/tstlang1.po: can't guess language
gettext: intl/tstlang2.po: can't guess language
      

Please ask the translator (identified by the Last-Translator field in the PO file), the language team (identified by the Language-Team field) or debian-i18n for a fix.

There are no up-to-date PO files in your package. You should call for translations before uploading to unstable.

You can send a call for translation using the podebconf-report-po command (package po-debconf):

        cd <po directory>
        podebconf-report-po --call