Dear all,
in a regular MediaWiki installation switched to de-formal, all help links point to the English versions. This is probably because there is not de-formal version of the MediaWiki documentation, which of course is fine. But all links to SpecialMyLanguage should lead to the German documentation, for settings of "de", "de-formal", "de-at" etc.
As an example: the help icon on Special:Recent changes leads to https://meta.wikimedia.org/wiki/Special:MyLanguage/Help:Recent_changes
But if you set your wiki to de-formal, it will lead you to the English help pages instead the German ones.
Best, Bernhard