I use 3.13 and the plugin does work, but gets a bit banana's sometimes. I think it has to do with W3 Total Cache (I have NOT minified the js and css, because then it doesn't work).
What I get is the [Translate] link sometimes just shows up in random languages. It is always the first language on top of the selection popup box, but that could be any language. I have seen Arabic, Turkey and many more. Well mine should be in Dutch, which it many times is, but not always.
Not sure if it is related to what others say here in the forum, since the rest of the plugin functions.
Thank you and regards, Ron