About [[MediaWiki:Mobile-frontend-language-article-heading/en]]
FYI: The message documentation currenmtly says:
- A heading within the article the content of which lists the other languages available for this article: translate the message considering the list to have an undetermined number of items.
The latter is generally impossible when the list is visible, and the message has to mention the list, see mw:i18n#Pass the number of list items as parameters to messages talking about lists. With this message here however, it is fortunate that a sensible translation is possible without referring to the fact that there is a list, so PLURAL is not really needed, at least not for those translations that I am aware of.