Janáček’s opera subjects – the 300-year-old opera singer, the composer with a mad mother-in-law, the Siberian prison camp – are by any standards a fairly rum collection. But The Cunning Little Vixen is arguably the most deviant of the whole bunch. Its foxy heroine (out of a Prague newspaper cartoon strip) is captured by the local Forester, lectures his hens about their subservience to the Cockerel, slaughters the lot of them, runs off, marries, starts a family, then allows herself to be shot by the poacher. All very charming, random and pathetic, one might feel.

Last week Lulu, this week Cio-Cio San, next week the Vixen Bystrouška. These are the three exemplars of David Pountney’s “Free Spirits” – as he labels his first themed season with WNO. But it’s hard to see poor little Butterfly, pinned to a board by the cruel American sailor-lepidopterist, as a free anything. Like a trapped fly, Suzuki calls her; and if there’s a free spirit in Puccini’s opera, it might rather be Pinkerton himself, “dropping anchor at random,” as he boasts to Sharpless: not such an inspiring thought.

What-ifs and might-have-beens are usually as pointless in music as in any other walk of life. Still one can’t help wondering how Alban Berg would have completed – and, no less interesting, revised – his opera Lulu, if he hadn’t been stung by some philistine insect in the summer of 1935 and died of the resulting septicaemia that Christmas Eve, with the last act unfinished and barely half-orchestrated.

Speaking about the Requiem he composed in 1990 in memory of the London Sinfonietta’s long-time artistic director Michael Vyner, Hans Werner Henze always talked as a believing atheist. “Paradise is here or ought to be,” he insisted, “not later, when nothing else happens;” and “In this world there is no hereafter, only presence: you can meet angels and devils in the street at any time.”

For some reason, the Welsh have revived their Così fan tutte, from last year, with positively unseemly haste – if not quite so unseemly as the haste with which their La Bohème, from this spring, was wheeled back on last month barely three months after its first airing. It looks as if the outgoing intendant John Fisher, never notable for lively repertory planning, was either clearing his desk, or had simply scarpered.

Reviewing the Buxton Festival production of Handel’s Jephtha on theartsdesk a couple of months ago, Philip Radcliffe complained that the director, Frederic Wake-Walker, had done too little to justify the staging of this, the composer’s last oratorio: had made it, that is, too static and unstagey. I wonder what Radcliffe would say about Katie Mitchell’s production for Welsh National Opera, revived this weekend by Robin Tebbutt, and a classic case of a director’s reluctance to allow an essentially statuesque, slow-moving work its natural space and pace.

Of all Romantic operas, La Bohème is perhaps the one that responds best to what one might, for want of a better phrase, call straight theatrical treatment. It’s pure genre: no hidden meanings, no contemporary significance. “Scenes from the life”, as Murger called his book, now barely readable. Puccini’s opera, likewise, is short on continuity, long on atmosphere, very long on sentiment. Why would anyone bother with it?

Welsh National Opera has a good track record with Wagner. Its Meistersinger of two summers ago is already the stuff of legend (and alas not likely to return to reality); farther back one recalls a more than respectable Parsifal, a notable Ring cycle, and an old Tristan under Goodall that’s still talked about in hushed whispers.

Such a pity about Beatrice and Benedict! As a musical visualiser, a creator of musical tableaux, a radio composer avant la lettre, Berlioz had few equals. The Damnation of Faust is surely the greatest radio opera ever written. But for some reason he had no grasp of the stage. Benvenuto Cellini is a lifeless succession of spectacular tableaux. The Trojans must have more superb music per square yard of ineffective drama than any work of comparable length.

Famously, at its Venice premiere in 1853, La traviata had trouble with the censor, not only over the salty innuendos of the plot, but over the simple fact that it was set in the present day and in contemporary costume. A rule like that would finish off most updated modern stagings (and no bad thing at that). But David McVicar’s now two-year-old staging of Verdi’s early verismo masterpiece in Cardiff's Wales Millennium Centre wouldn’t be one of them.