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 turtleart 's PO files:

gettext: po/cpp.po: cpp not a language code
gettext: po/ff.po: ff not a language code
gettext: po/kos.po: kos not a language code
gettext: po/mvo.po: mvo not a language code
gettext: po/pap.po: pap not a language code
gettext: po/pis.po: pis not a language code
gettext: po/pseudo.po: can't guess language
gettext: po/tpi.po: tpi not a language code
gettext: po/tvl.po: tvl not a language code
gettext: po/tzo.po: tzo not a language code
      

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.