I have noted an increase of discussion on English Wikipedia in languages other than English lately. For now, I'll forgo naming languages and listing particular offenders here.
Offenders?
Do we have a policy on this? Should we?
My opinion is that we should not allow or least sternly frown upon discussion on the English Wikipedia in languages other than English.
Why? Every day, thousands of discussions take place on Wikipedia of which I have no knowledge, because I don't read them.
If I were actively engaged in editing a page, AND other people were conducting discussions which I could not understand, AND the result of those discussions were edits that I did not agree with, AND THEN they refused to engage with me in genuine discussions in English of the points in dispute-- then, sure, I'd take it to RfC.
If they're editing a page written in English, there's a reasonable presumption that they know enough English to talk to me, so refusal to do so can be reasonable interpreted as "failure to engage."
But my beef would be "failure to engage," not "discussion amongst themselves in a language I don't understand."
Besides, bad as they are, the automated translation services such as babelfish.altavista.com are usually good enough to at least understand the subject being discussed in a foreign language, and tell whether it's actually germane to anything I need to know about.
(We allow Cabal members to communicate with each other via secret code words and steganography in Wikipedia images, so how is this different?)