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 vim 's PO files:

gettext: src/po/ja.sjis.po:530:33: invalid control sequence
src/po/ja.sjis.po:579:18: invalid control sequence
src/po/ja.sjis.po:721:13: invalid control sequence
src/po/ja.sjis.po:858:16: invalid control sequence
src/po/ja.sjis.po:894:24: invalid control sequence
src/po/ja.sjis.po:1040:30: invalid control sequence
src/po/ja.sjis.po:1096:28: invalid control sequence
src/po/ja.sjis.po:1105:18: invalid control sequence
src/po/ja.sjis.po:1329:15: invalid control sequence
src/po/ja.sjis.po:1461:26: invalid control sequence
src/po/ja.sjis.po:1464:29: invalid control sequence
src/po/ja.sjis.po:1699:32: invalid control sequence
src/po/ja.sjis.po:1723:68: invalid control sequence
src/po/ja.sjis.po:1726:49: invalid control sequence
src/po/ja.sjis.po:1744:52: invalid control sequence
src/po/ja.sjis.po:1747:41: invalid control sequence
src/po/ja.sjis.po:1769:36: invalid control sequence
src/po/ja.sjis.po:1794:37: invalid control sequence
src/po/ja.sjis.po:2003:33: invalid control sequence
src/po/ja.sjis.po:2429:16: invalid control sequence
msgfmt: too many errors, aborting
      

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.