Booklet of Arte Nova Contemporary 74321 40737 2 (scanned in the rip at rips/Hummel - Gesualdo, Shambadal/scans/scannen0002.jpg): "Franz Hummel (*1939) / Gesualdo - Opera in two acts / Libretto: Elisabeth Gutjahr". The work is in German - the scene titles on the disc are German (Leichenschmaus, Hochzeit, Hochzeitsnacht, Die Geburt des Thronfolgers, Giulios Verrat, Liebesnacht, Mord) and so are the role names already in this record (Herzog von Andria, Papst, Kardinal Alfonso Gesualdo). Language and librettist were both unset.

Wikipedia article: https://en.wikipedia.org/wiki/Carlo_Gesualdo