Will Ferrell is not the most convincing actor (and in this film his age jars), but he is funny and can write funny, and in “Eurovision Song Contest: The Story of Fire Saga,” he tackles a worthy target, the music phenomenon that I personally abhor but is undeniably a global unifying musical phenomenon. The storyline is as kitsch as the subject matter, with Icelandic lifelong music partners Lars (Ferrell himself) and Sigrit (a wonderful performance by Rachel McAdams) chase their Eurovision dream against seemingly impossible odds. In quasi-mockumentary style, we accompany Lars and Sigrit, a bumbling pair with some decent Abba-style songs, to the finals in Edinburgh, where mayhem and bubblegum music and extravaganzas reign. The script surely intends us to be sympathetic to the duo, but that interferes with the comedy, and the number of truly comic scenes (a couple of madcap ones, one in which Lars insults blithe American tourists) is way lower than it should be. The cast of Eurovision aspirants is strong, especially Dan Stevens (one of my favorite actors) playing an oily but somehow charming Russian superstar. Bubbling under the surface of what surely one might expect to be a manic satire is genuine affection for the Eurovision scene, and that accords “Eurovision Song Contest: The Story of Fire Saga” with its own gravitas but saps the hope of laughs. Overall, a diversion with some funny moments.