It is currently not possible to search all languages
unless you search through an external search engine, but I
don't think most people realise how this works, and the
convenient links to other search engines won't be
available once we get the new database servers.
I show below an unsigned comment that came from
[[Meta:Wikimedia site feedback]]:
Today I was looking for "Kalignost" which happens to be a
german brandname for tetraphenylborate. The english
language search didn't come up with anything, not even
links to "other languages" ... with reference to the
previous point, I would think this could be helpful ...