Works (sometimes...) Rated 2 out of 5 stars
I use this Addon since a few years and it worked well sometimes.
I say sometimes, because I use it on a WebSite and it shows me a window with translation, and on the same WebSite some hours later (w/o FF restart) it does nothing.
I use it on MAC and WIN and on WIN it creates a lot of 0-byte files in its configuration folder.
Also, if I change the config too often or delete predefined translation-sites, it does not work anymore.
So I must say, it works (5 stars)...sometimes (-2), when I not change the config (-1)