There’s a lot to be said for concert performances of Wagner. Not only are you spared the post-prandial lucubrations of aspirant directors – the moonmen and the fighter pilots, the jackboots and the biogas installations. But it’s possible to concentrate on Wagner’s greatest theatrical gift: not his stagecraft or stage imagery, but his management of time and psychological growth through purely musical means.

I do wish that arts institutions would stop using the word “immersive” when they simply mean “staged”. Just to be clear, there is nothing “immersive” about Netia Jones’s new staging of Georg Friedrich Haas's song-cycle ATTHIS at the Royal Opera House’s Linbury Studio, whatever the blurb may say. The director’s signature video projections, dance, song and music, come together to create an exquisite, hypnotic piece of very traditional theatre – not a promenade or a broken fourth wall in sight. And it’s all the better for it.

Even at the tragic heart of Janáček's Jenůfa there is ambiguity. As the Kostelnička or village sacristan takes her stepdaughter Jenůfa’s baby boy outside to drown it in the icy river, you cannot quite be sure whether she is motivated by pride, fear or her love for Jenůfa. In this poised new co-production by Scottish Opera and Danish National Opera, there is no doubt that she is driven by love. Murderous it may be, and it will nearly destroy her, but her compassion cannot be denied.

When does a Gilbert and Sullivan chorus make you laugh, cry and cheer as much as any of the famous set pieces? In this case when Major-General Stanley’s daughters “climbing over rocky mountain” wear pretty white dresses but turn out to be gym-trained showboys from the waist up, with their very own hair. That’s already one extra dimension to an operetta gem, but there’s so much more to enjoy around the crisp delivery of Gilbert’s undimmed lyrics.

A journey into dreams through songs from Dowland to The Kinks; a Swiss director who, Covent Garden’s Director of Opera Kasper Holten assures us, is “one of the most important European theatre artists”; a Norwegian chanteuse who, I assure you, is a performer of real originality. All that should add up to something just a little bit extraordinary, shouldn’t it? Sadly not. What I saw last night was the kind of thing I’d shrug off having chosen at random from offerings at the Edinburgh Fringe.

Composer Tansy Davies and librettist Nick Drake’s opera Between Worlds cannot help but be a devastating tribute to the tragedy of 9/11. Yet the whole is peppered with problems that mean this result is achieved only intermittently. Davies – whose first opera this is – and the playwright Drake, with Deborah Warner directing, have picked a topic that would seem at first glance to demand the scale of a modern-day Götterdämmerung. The result they extrapolate is far from that – but when it does succeed, it is in ways that are not really about 9/11 at all.

There was a moment half-way through Jonathan Dove’s children’s opera Swanhunter when I suddenly realised why pantomime developed its convention of the principal boy. Having a grown man prancing and posturing boyishly for the entertainment of a room full of kids feels odd, affected somehow, distorting the simplicity and sincerity of the tale being told. Which is a shame when, as here, the theatrical trappings are so vivid and enticing.

Still they keep coming, 35 years on from the London premiere of Sondheim's "musical thriller": Sweeneys above pubs, in pie shops, concert halls and theatres of all sizes, on the big screen, Sweeneys with symphony orchestras, two pianos or a handful of instruments wielded by the singers, Sweeneys as musicals and as operas, the dumpy and the tall. Which type was this one? Not a vintage English National Opera production, that much seems clear.

All Savoyards, whether conservative or liberal towards productions, have been grievously practised upon. They told us to expect the first professional London grappling with Gilbert and Sullivan’s eighth and, subject-wise, most problematic operetta in 20 years (23, if the reference is to Ken Russell’s unmitigated mess, one of English National Opera’s biggest disasters). Yet this is not Princess Ida as the pair would recognize it.

Johann Christian Bach’s Amadis de Gaule, which is receiving its first London run this week in a vivid and charming production at University College London Opera this week, suffered like many a talented work from the blinkered whims of musical fashion. History has generally focused on more pressing issues in late 18th-century Paris than the operatic rivalry between the schools of Gluck and Piccinni, but Bach’s failure to please either faction along with the minor disturbances of 1789 has, it’s believed, caused the subsequent neglect of this poignant and sensuous piece.