Last modified: 2013-02-27 08:33:14 UTC
It is not possible to change the language settings via Wikidata:Main Page using the language links there. You can only change the language for the main page but not for the user interface. The language choose-button is only available for logged-in users, so I think that bug is difference then Bug 30047
Confirming, though not sure if it's specifically a Wikidata issue. Wondering if ULS (UniversalLanguageSelector) could be enhanced for this (though it requires login currently).
*** This bug has been marked as a duplicate of bug 42186 ***