BK, with your interest in mittel-European opera, have you turned your attention to Russian opera? I think you might enjoy these.
I am crazy about Tchaikovsky's Eugene Onegin. I got to see Mirella Freni's portrayal of Tatiana, and she's so wonderful in the role. I like this DG recording quite a l;ot.
I've seen Lady Macbeth of Mtsenk onstage and on video, but I have never listened to it, so you might prefer another recording, but I think Shostakovich's blend of satire and erotomania is quite fascinating. I was really surprised by the last Met production by the number of nude men onstage, but it was apropos for the leading lady's sexual frustration.
Prokofiev's The Love for Three Oranges was first performed in French by Mary Garden's opera company, so I prefer it in that language. There's a CD available in a translation by Tom Stoppard as well. The opera is a combo of commedia dell'arte, fairy tale, and satire.
Mussorgsky's great Boris Godunov, not spy Boris Badunov of Rocky and Bullwinkle fame, has been revised by both Rimsky-Korsakov and Shostakovich, and there is also a huge 3-CD set of several versions of Mussorgsky's original work, It was Rimsky-Korsakov's version that made the opera popular, and Karajan and company do it with all the glitter and glory possible. The Coronation Scene is glorious.