Opera Rara are opera's great archaeologists, mining the forgotten works of yesteryear in a bid to unearth hidden treasures. This year's dig is Bellini's first opera Adelson e Salvini, which was performed in concert at the Barbican last night, after Opera Rara's usual week of recording, with the BBC Symphony Orchestra and Daniele Rustioni. Had they uncovered a gem, one wondered, or a mere historical curiosity? The answer, this year, was somewhere in between – a semi-precious stone, perhaps.

Rustioni was his usual bundle of energy, getting a performance from the BBCSO that was precise, clean and brisk. Strings were accurately together and bright in tone, woodwind and horns nicely distinguished, Rossinian crescendi delivered with balance and verve. Bellini's orchestration is always easy on the ear, and Rustioni made it sparkle. This wasn't the most nuanced of interpretations, however: slower passages might have been given more time to breathe and long melodic arcs might have been smoother.

The show-stealing star of the evening was Maurizio Muraro in the role of Salvini's servant Bonifacio. Muraro was the complete basso buffo: his comic manner and stage presence brought the house down, his rapid-fire patter superbly executed. At the same time, this is a warm and powerful voice: when his music turned to occasional flashes of lyricism, his timbre was a joy to listen to. It's a voice I will travel to hear again.

Bonifacio is the only fully buffo role in Adelson e Salvini, and the fact that this was the highlight of the evening tells you something about the work's weaknesses. This is an "opera semi-seria", an attempt to combine seriousness and farce. The basis is a gothic tale of dastardly deeds as the beautiful Nelly's disgraced uncle Struley attempts to kidnap her (for the second time) from her guardian and fiancée "milord" Adelson; matters are not helped when, in Adelson's absence, his best friend, the penniless Italian painter Salvini, also falls for Nelly.

Evenly mixing dramatic and farcical elements in opera is a difficult trick to pull off: Don Giovanni (labelled a dramma giocoso) is the only example I can think of that's an unqualified success. But Andrea Leone Tottola, Bellini's librettist, doesn't have the quality of Da Ponte (or, for that matter, of Bellini's later librettist Felice Romani), and Adelson e Salvini falls between the two stools. The serious parts aren't compelling enough to be really dramatic, with big dramatic moments often resulting from somewhat laughable misunderstandings, so you're not sure if they're intended to be humorous or not, while the whole thing doesn't really have the pace or verve of a proper opera buffa.

With a lot of changes from the cast originally advertised, vocal performances were mixed. Neither lead role impressed in the first half: Daniela Barcellona (Nelly) showed pleasant, warm timbre, but struggled to come through clearly above the orchestra and didn't provide a great deal to thrill in the way of decoration. In the tenor role of Salvini, Enea Scala had a lot of things right about his voice (phrasing, articulation, flexibility), but oversinging resulted in an unpleasant, slightly reedy timbre. Scala improved considerably in the second half, producing a knockout aria in Act III as he accuses himself of having accidentally killed Nelly. Other performances were solid: Simone Alberghini was a mellifluous Adelson, Rodion Pogossov an amusingly villainous Struley.

I'm glad to have seen Adelson e Salvini for its historical interest: it offers a fascinating snapshot of Bellini's development as a composer, and there are plenty of vocal numbers and snatches of orchestral music to admire. But last night didn't do enough to convince me that it's a work that can stand on its own two feet.