I've never heard a good art song since Akiko Shikata's "Sorriso" -- beautiful chords, expressive piano, and equally expressive voice. The only thing I would recommend apart from everything you've done, is to drag the ends of "prosperita," "sincerita" a little bit -- not too much, just a little bit more than already is the case in the song now -- just to give it that bit more gravitas.
I've not been the best at dissonance but can recognise when it's well done -- and this is one of the best cases of it that I've ever heard.
Thoroughly enjoyed this one. Giving this a well-deserved 5.