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 scummvm 's PO files:

gettext: devtools/create_supernova/strings1-en.po:39:8: invalid multibyte sequence
devtools/create_supernova/strings1-en.po:44:14: invalid multibyte sequence
devtools/create_supernova/strings1-en.po:49:10: invalid multibyte sequence
devtools/create_supernova/strings1-en.po:74:13: invalid multibyte sequence
devtools/create_supernova/strings1-en.po:94:8: invalid multibyte sequence
devtools/create_supernova/strings1-en.po:99:14: invalid multibyte sequence
devtools/create_supernova/strings1-en.po:104:10: invalid multibyte sequence
devtools/create_supernova/strings1-en.po:147:11: invalid multibyte sequence
devtools/create_supernova/strings1-en.po:182:23: invalid multibyte sequence
devtools/create_supernova/strings1-en.po:210:14: invalid multibyte sequence
devtools/create_supernova/strings1-en.po:240:13: invalid multibyte sequence
devtools/create_supernova/strings1-en.po:240:14: invalid multibyte sequence
devtools/create_supernova/strings1-en.po:240:28: invalid multibyte sequence
devtools/create_supernova/strings1-en.po:255:13: invalid multibyte sequence
devtools/create_supernova/strings1-en.po:255:14: invalid multibyte sequence
devtools/create_supernova/strings1-en.po:255:34: invalid multibyte sequence
devtools/create_supernova/strings1-en.po:310:27: invalid multibyte sequence
devtools/create_supernova/strings1-en.po:314:36: invalid multibyte sequence
devtools/create_supernova/strings1-en.po:318:32: invalid multibyte sequence
devtools/create_supernova/strings1-en.po:348:14: invalid multibyte sequence
msgfmt: too many errors, aborting
gettext: devtools/create_supernova/strings2-en.po:35:8: invalid multibyte sequence
devtools/create_supernova/strings2-en.po:39:14: invalid multibyte sequence
devtools/create_supernova/strings2-en.po:43:10: invalid multibyte sequence
devtools/create_supernova/strings2-en.po:63:13: invalid multibyte sequence
devtools/create_supernova/strings2-en.po:79:8: invalid multibyte sequence
devtools/create_supernova/strings2-en.po:83:14: invalid multibyte sequence
devtools/create_supernova/strings2-en.po:87:10: invalid multibyte sequence
devtools/create_supernova/strings2-en.po:123:11: invalid multibyte sequence
devtools/create_supernova/strings2-en.po:151:14: invalid multibyte sequence
devtools/create_supernova/strings2-en.po:175:13: invalid multibyte sequence
devtools/create_supernova/strings2-en.po:175:14: invalid multibyte sequence
devtools/create_supernova/strings2-en.po:175:28: invalid multibyte sequence
devtools/create_supernova/strings2-en.po:187:13: invalid multibyte sequence
devtools/create_supernova/strings2-en.po:187:14: invalid multibyte sequence
devtools/create_supernova/strings2-en.po:187:34: invalid multibyte sequence
devtools/create_supernova/strings2-en.po:227:14: invalid multibyte sequence
devtools/create_supernova/strings2-en.po:239:13: invalid multibyte sequence
devtools/create_supernova/strings2-en.po:239:14: invalid multibyte sequence
devtools/create_supernova/strings2-en.po:303:13: invalid multibyte sequence
devtools/create_supernova/strings2-en.po:307:13: invalid multibyte sequence
msgfmt: too many errors, aborting
gettext: po/be-tarask.po: can't guess language
gettext: po/zh_Hans.po: can't guess language
gettext: po/zh_Hant.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.