(Photo: Fabrizio Sansoni) Rome’s Teatro dell’Opera opened its season with “Lohengrin,” last heard at the Teatro Costanzi a half century ago, in 1975. Once Wagner’s most popular opera in this country, it fell out of favor with the new dogma of presenting operas in their original language. Between 1933 and 1966, it was performed on average every other season. Then {…}