The quality header on pages in the "Page" namespace is shown in the wiki's content language rather than the user's interface language. This is a problem when trying to use the ProofreadPage extension on wikis which use more than one language or script.

For example:

On a page in the Chinese Wikisource with the interface in Traditional Chinese, the message is shown in Simplified Chinese.

On a page in the Multilingual Wikisource with the interface in Malay in Arabic script, the message is shown in English. It is also missing lang/dir tags in the HTML, so when viewing the same page in English, the header is still in English but is right-aligned, because of the page language not being English.