This is a great plugin and it's working fine. :)
But: it's not really compatible to qTranslate. They biggest problem is that notification emails are sent in the admin's language (best case. worst case would be the language of the commenter. I didn't check this.)
In order to send messages to each subscriber in their language you would have to save that somehow when subscribing.
The function qtrans_useCurrentLanguageIfNotFoundUseDefaultLanguage doesn't work here because it really returns the CURRENT language. I changed the plugin to use qtrans_use and provide the desired user languages. (which I save for each user as meta data with my own script, independent from qTranslate.)
BTW, to simply split the content by language you don't have to use qtrans_useCurrentLanguageIfNotFoundUseDefaultLanguage. use __(), qTranslate will do the rest.