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 fortran-toml 's PO files:

source does not specify a priority
gettext: doc/locales/es/LC_MESSAGES/tutorial.po:63: end-of-line within string
doc/locales/es/LC_MESSAGES/tutorial.po:63:11: syntax error
doc/locales/es/LC_MESSAGES/tutorial.po:64: end-of-line within string
msgfmt: found 3 fatal errors
      

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.