I managed to find that http://www.wikidata.org/w/index.php?title=Q21193&action=edit&redlink=1 was a duplicate only because I correctly guessed that the IP which created it did so in Italian. If this was in, for example, Arabic, I would have had no way of telling what this newly-made page had as its content without first trying to guess the correct language - not even with Special:Undelete.
This isn't as bad for diffs because the edit summaries automatically show which language the change was made in, but for the first edit that creates the entry, I have no such aid, as the edit summary says nothing about the language used.
One possible remedy may be a "view all languages" option, either as a special page or another tab, or, perhaps more easily, show which language the initial edit was made in.
Version: unspecified
Severity: normal