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 stellarium 's PO files:

gettext: po/stellarium-desktop/es_419.po: can't guess language
gettext: po/stellarium-landscapes-descriptions/es_419.po: can't guess language
gettext: po/stellarium-metainfo/es_419.po: can't guess language
gettext: po/stellarium-planetary-features/es_419.po: can't guess language
gettext: po/stellarium-remotecontrol/es_419.po: can't guess language
gettext: po/stellarium-scenery3d-descriptions/es_419.po: can't guess language
gettext: po/stellarium-scripts/es_419.po: can't guess language
gettext: po/stellarium-skycultures-descriptions/es_419.po: can't guess language
gettext: po/stellarium-skycultures/es_419.po: can't guess language
gettext: po/stellarium-skycultures/mo.po: mo not a language code
gettext: po/stellarium/es_419.po: can't guess language
gettext: po/stellarium/mo.po: mo not a language code
gettext: po/stellarium/te.po:4739: 'msgid' and 'msgstr' entries do not both end with '\n'
msgfmt: found 1 fatal error
      

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.