The feature of showing another translation beside as an aid to people who's first language isn't English is a great idea - I'm surprised it's news.
One thing I always wondered is whether you can set a list of languages for GNU/Linux systems to display things in. I've never seen that.
For example, if I'm a native Ilonggo speaker, and my second language is Tagalog, and third is English, how do I specify that?
If I just set my language to Ilonggo, then I'm going to get most things in English since translations to Ilonggo are rare. So I'll probably set my language to Tagalog, since translations to Tagalog are pretty common. The end result is that I get messages that are less good than they could be, and if someone did translate things to Ilonggo, their work is being somewhat wasted.