“It’s like you’re changing channels’’ - that’s how Augusta Read Thomas, director of this year’s Festival of Contemporary Music at Tanglewood, described her programming to Richard Dyer, the former Globe critic, in Monday’s pre-concert conversation. Dyer, for his part, called it “the most diverse’’ he had attended. The festival’s second half continued that consistent inconsistency. Monday night brought the Tanglewood Music Center Orchestra to the stage. The first half carried nationalistic echoes. Enrico Chapela’s “Ínguesu’’ orchestrally maps the 1999 FIFA Confederations Cup final, in which Mexico upset Brazil: individual players represented by individual instruments, the structure matching the match’s ebb and flow, the conductor-referee even flashing yellow and red cards. But the exuberance also echoed the piled-up rhythms of Latin American composers like Revueltas and Ginastera. Julian Anderson’s “Shir Hashirim,’’ a gorgeous Song of Songs setting (gorgeously sung by soprano Rosa Betancourt), threaded ecstatically ornamented chant, reminiscent of Anderson’s countrymen Tippett and Purcell, through a bright, saturated shimmer.