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 pymupdf 's PO files:

gettext: docs/locales/ja/LC_MESSAGES/algebra.po:129:83: syntax error
msgfmt: found 1 fatal error
gettext: docs/locales/ja/LC_MESSAGES/document.po:1155:12: syntax error
docs/locales/ja/LC_MESSAGES/document.po:1155: keyword "UTF" unknown
docs/locales/ja/LC_MESSAGES/document.po:1156: end-of-line within string
docs/locales/ja/LC_MESSAGES/document.po:1160: end-of-line within string
docs/locales/ja/LC_MESSAGES/document.po:1167:12: syntax error
docs/locales/ja/LC_MESSAGES/document.po:1168: end-of-line within string
docs/locales/ja/LC_MESSAGES/document.po:1170: end-of-line within string
docs/locales/ja/LC_MESSAGES/document.po:1178:12: syntax error
docs/locales/ja/LC_MESSAGES/document.po:1179: end-of-line within string
docs/locales/ja/LC_MESSAGES/document.po:1182: end-of-line within string
msgfmt: found 10 fatal errors
gettext: docs/locales/ja/LC_MESSAGES/page.po:6520: duplicate message definition...
docs/locales/ja/LC_MESSAGES/page.po:1383: ...this is the location of the first definition
docs/locales/ja/LC_MESSAGES/page.po:6841: duplicate message definition...
docs/locales/ja/LC_MESSAGES/page.po:2884: ...this is the location of the first definition
msgfmt: found 2 fatal errors
gettext: docs/locales/ja/LC_MESSAGES/pymupdf4llm/api.po:74: keyword "words" unknown
docs/locales/ja/LC_MESSAGES/pymupdf4llm/api.po:74:101: syntax error
docs/locales/ja/LC_MESSAGES/pymupdf4llm/api.po:75: keyword "words" unknown
docs/locales/ja/LC_MESSAGES/pymupdf4llm/api.po:92: keyword "page" unknown
docs/locales/ja/LC_MESSAGES/pymupdf4llm/api.po:92:290: syntax error
docs/locales/ja/LC_MESSAGES/pymupdf4llm/api.po:110: keyword "png" unknown
docs/locales/ja/LC_MESSAGES/pymupdf4llm/api.po:110:75: syntax error
docs/locales/ja/LC_MESSAGES/pymupdf4llm/api.po:135: keyword "metadata" unknown
docs/locales/ja/LC_MESSAGES/pymupdf4llm/api.po:135:20: syntax error
docs/locales/ja/LC_MESSAGES/pymupdf4llm/api.po:138: keyword "toc_items" unknown
docs/locales/ja/LC_MESSAGES/pymupdf4llm/api.po:138:21: syntax error
docs/locales/ja/LC_MESSAGES/pymupdf4llm/api.po:141: keyword "tables" unknown
docs/locales/ja/LC_MESSAGES/pymupdf4llm/api.po:141:18: syntax error
docs/locales/ja/LC_MESSAGES/pymupdf4llm/api.po:153: keyword "words" unknown
docs/locales/ja/LC_MESSAGES/pymupdf4llm/api.po:153:138: syntax error
docs/locales/ja/LC_MESSAGES/pymupdf4llm/api.po:171: keyword "lines_strict" unknown
docs/locales/ja/LC_MESSAGES/pymupdf4llm/api.po:171:119: syntax error
docs/locales/ja/LC_MESSAGES/pymupdf4llm/api.po:172: keyword "lines_strict" unknown
docs/locales/ja/LC_MESSAGES/pymupdf4llm/api.po:180: keyword "picture" unknown
docs/locales/ja/LC_MESSAGES/pymupdf4llm/api.po:180:103: syntax error
msgfmt: too many errors, aborting
gettext: docs/locales/ko/LC_MESSAGES/page.po:5122: duplicate message definition...
docs/locales/ko/LC_MESSAGES/page.po:5119: ...this is the location of the first definition
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.