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:

source does not specify a priority
gettext: src/po/ja.sjis.po:261:12: invalid control sequence
src/po/ja.sjis.po:548:33: invalid control sequence
src/po/ja.sjis.po:597:18: invalid control sequence
src/po/ja.sjis.po:739:13: invalid control sequence
src/po/ja.sjis.po:880:16: invalid control sequence
src/po/ja.sjis.po:916:24: invalid control sequence
src/po/ja.sjis.po:1062:30: invalid control sequence
src/po/ja.sjis.po:1118:28: invalid control sequence
src/po/ja.sjis.po:1127:18: invalid control sequence
src/po/ja.sjis.po:1351:15: invalid control sequence
src/po/ja.sjis.po:1486:26: invalid control sequence
src/po/ja.sjis.po:1489:29: invalid control sequence
src/po/ja.sjis.po:1740:32: invalid control sequence
src/po/ja.sjis.po:1764:68: invalid control sequence
src/po/ja.sjis.po:1767:49: invalid control sequence
src/po/ja.sjis.po:1785:52: invalid control sequence
src/po/ja.sjis.po:1788:41: invalid control sequence
src/po/ja.sjis.po:1810:36: invalid control sequence
src/po/ja.sjis.po:1835:37: invalid control sequence
src/po/ja.sjis.po:2044:33: 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.