Long before the English-speaking pop mainstream took real notice, BTS were already global pop stars. The successes the K-pop outfit have had in this country happened largely without worrying about how it might or might not fit in. On its new release, “Map of the Soul: Persona,” it showcases its highest-profile collaborations to date in a way that preserves its core strengths. The shimmering “Boy With Luv” features Halsey — but more importantly, it features Halsey singing in Korean, exactly the sort of bilingual exchange that’s all too rare. And “Make It Right” is in part written by Ed Sheeran. It has some of his signature soft-soul gestures, but BTS renders them with complexity. The least comfortable collaborations are the ones in which the balance of power is wildly uneven, where one party badly needs something from the other. But all you hear on these songs is mutual respect. JON CARAMANICA