It’s a truism that great music transcends national borders. Yet there’s a craggy mystique about Jean Sibelius to which his Finnish compatriots seem more keenly attuned than other interpreters. Audiences at Severance Hall may test this hypothesis as Helsinki-born Susanna Mälkki leads his symphonic poem En Saga as well as his Symphony No. 1. In between, Mälkki presents her internationalist credentials with the Violin Concerto of Oliver Knussen, a British composing prodigy who in maturity never lost the rambunctious energy of his youth. The virtuoso solo part is in the MacArthur-anointed hands of Leila Josefowicz. —M.G.