The British English localisation contains a number of other, likely unintentionally-included languages, which override the intended core English translation.
Steps to replicate the issue:
- An example affected component is the file history table. Visit a file page of a vanilla wiki, for example https://aew.freosanstudios.com/w/index.php/File:Schindler_Service_Passage.jpg
- If the wiki's language is not already British English, place ?uselang=en-gb in the URL.
- Scroll down to the File history section.
What happens?: Certain messages are in unexpected languages. For example, the message "filehist-datetime" displays "Gwalagizhi", which is from Hausa, and "filehist-thumb" displays "Nyangagi" from Indonesian.
What should have happened instead?: The aforementioned messages should have shown the same messages as from the core English translation (c.f. the same page with ?uselang=en, for example https://aew.freosanstudios.com/w/index.php/File:Schindler_Service_Passage.jpg?uselang=en)
Software version (on Special:Version page): 1.39.8. However, the issue affects all current MediaWiki versions due to being a translatewiki.net bug.
Other information (browser name/version, screenshots, etc.): There are some other messages in en-gb.json affected by this issue, such as "editundo". Before the translation issue occured, it seems that the affected message keys were simply not defined, which causes them to default to equivalents in en.json and is reasonable.
Appears to be a continuation of T286901: Explore options to avoid people translating into wrong language.