I don't understand the languages of most of the lieder I listen to, but, I do know what the songs are about from having read the translations. I think this does ad to the experience.
There are plenty of songs that are sung in English, such as those of Eric Whitacre that I mentioned above. Another living American song composer that is quite interesting is Craig Urquhart. British mid-century composers, like Britten, also wrote some interesting songs too.