Common wisdom has it that the prolific output of 20th century Czech genius Bohuslav Martinů is very uneven, a judgment surely made without a complete hearing. Some listeners shrink from his fidgety polystylism. Many of us on the fringes of the Martinů hardcore, though, have found ourselves giddy with each new discovery of music we didn't know before: last year, string duos on a CD from viola-player Maxim Rysanov, this year piano trios from the Czech label Supraphon and now two one-act operas, this time live from Guildhall students.

Seventy years ago, almost to the month, Welsh National Opera took to the stage for the first time with a double bill of the terrible twins, Cavalleria rusticana and Pagliacci; and fifty years later the company celebrated with the same two works directed by Elijah Moshinsky, designed by Michael Yeargan. To repeat the exercise in the same productions after another twenty years might seem an egregious piece of navel-gazing. But Moshinsky made a clever point with his 1996 staging, about stylistic distances travelled and technical standards raised.

We don’t hear much about composer Stanisław Moniuszko in the West, but in Poland he’s considered a key figure in the history of opera. Moniuszko’s statue stands at the entrance of the National Opera House in Warsaw, and inside he’s depicted by several busts and portraits. In the second week of May, the venue hosted not only the Ninth International Stanisław Moniuszko Vocal Competition but also – in its Moniuszko Auditorium – Straszny dwór (The Haunted Manor), one of his most famous works.

New operas are a risky business, or so the Royal Opera’s past experience teaches us. For years, visiting the company’s Linbury Studio Theatre was like rolling the dice while on a losing streak: vain, desperate hope followed inevitably by disappointment. Glare, The Virtues of Things, Clemency, the failed experiment that was OperaShots. But recently things have taken a turn. Gradually, thanks to works from Birtwistle, Haas and more, the risk has begun to pay off.

"Unjustly neglected masterpiece" is a cliché of musical criticism, and usually an exaggeration. Romanian master Enescu's vast journey through aspects of the Oedipus myth seemed like an unacknowledged great among 20th century operas through the medium of the starrily-cast EMI recording with José van Dam as the noblest Greek of all; after Martinu's Julietta and Szymanowski's King Roger, here was the last titan to be properly served by a top UK production.

"We're off to Glyndebourne, to see a ra-ther bor-ing op-ra by Rosseeeni," quoth songwriting wags Kit and the Widow. So here it was at the Sussex house after a 34-year absence, the most famous of all his operas which includes the overture’s oboe tune to which those words were set, and it wasn't possible that The Barber of Seville, pure champagne, could ever be boring. Or was it? Never underestimate the power of vaguely-conceived direction to rob musical wit and precision of their proper glory.

A celebration of the power of words and music (leaving aside, briefly, that more troubling business about the Fatherland), Wagner’s Die Meistersinger von Nürnberg is a natural opener for the summer opera season. Art triumphs over all, but in David McVicar’s production it’s a triumph of peculiarly human complication – a victory that leaves a hero in tears, that crowns some of opera’s most reactionary stick-in-the-muds with laurels, and leaves us asking: did Eva really pick the right man?

What Auden called "the sexy airs of summer" arrived early in Göttingen this year. Frog action in the Botanical Gardens of the town's pioneering University may have been less clamorous than when I first came here in late rather than early May (the annual International Handel Festival usually begins whenever the Ascension Day holiday happens to be, so it's a moveable celebration).

There’s a beautiful moment at the start of Act II of Anthony Minghella’s Madam Butterfly. Butterfly kneels, leaning forward to kiss Pinkerton, seated in his defiantly Western armchair. A paper screen moves swiftly across our view, and almost before it has passed he is gone, just another evanescent vision in this gorgeous, ephemeral world where cherry blossom no sooner flowers than it fades and falls.

War may be a dramatic affair for anyone involved in it, but staging it is another matter. In fact describing it satisfactorily at all needs either a Tolstoyan flair for the large canvas, or else a poetic genius for directing its force inwards, into self-reflection or religious contemplation or the kind of intense verbal music, rich in historical and literary allusion, that the great Welsh artist and writer David Jones made his own in his long, tragic prose-poem, In Parenthesis.