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 picard 's PO files:

gettext: po/attributes/zh-Hans.po: can't guess language
gettext: po/attributes/zh_Hans.po: can't guess language
gettext: po/attributes/zh_Hant.po: can't guess language
gettext: po/constants/zh_Hans.po: can't guess language
gettext: po/constants/zh_Hant.po: can't guess language
gettext: po/countries/es_419.po: can't guess language
gettext: po/countries/zh-Hans.po: can't guess language
gettext: po/countries/zh_Hans.po: can't guess language
gettext: po/countries/zh_Hant.po: can't guess language
gettext: po/es_419.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.