Not quite a musical, sort of a folktale, and almost but not entirely a hardscrabble hunk of post-war realism before all of a sudden changing gears, “Scarlet” – which opened the 2022 Cannes Film Festival’s Directors’ Fortnight sidebar on Wednesday – is a tricky project to pin down. Of course, director Pietro Marcello wouldn’t have it any other way.Shooting in French for the first time, the Italian filmmaker made his name with documentaries before working found and historical footage into the world of make-believe with 2019’s “Martin Eden.” With this more ambitious (if more uneven) follow-up, Marcello continues at a similar pace, folding fact into fiction as he explores both the landscapes of rural Normandy in the aftermath of the First World War and the plight of the working poor, all through the crags of his leading man’s brow.That brow (and those crags) belongs to Raphael (Raphaël Thiéry), who we discover limping home from the front interspersed with historical footage of fellow soldiers doing the same.