A few more baroque aria suggestions - they all move, but while melismatic in parts, they do not require virtuosic fioratura - in Italian and French. If you decide on a German art song, and you choose the French aria, you'd still be showing three languages.

Handel: "Prigioniera ho l'alma in pena" - RODELINDA

Gluck: "Quel nouveau ciel" - ORPHÉE ET EURYDICE

Vivaldi: "Deh ti piega, deh consenti" - LA FIDA NINFA

Or you could always do:

Mozart: "Il mio tesoro" - DON GIOVANNI