The message wikibase-anonymouseditwarning links to a Wikipedia article in English, and its qqq documentation tells translators to link to the relevant Wikipedia article.

It will be more robust to use a Special:GoToLinkedPage link instead, something like this: https://www.wikidata.org/wiki/Special:GoToLinkedPage?site=LANGwiki&itemid=Q11135 ("LANG" will have to be replaced by the language).

This way won't cover languages in which there is no article, but they aren't covered anyway, and this will be more robust.