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 eglibc 's PO files:

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