The music we hear in the trailer is by Mark Mancina and Opetaia Foaʻi. Mark Mancina did the 3rd biggest selling Disney soundtrack (after The Lion King and Frozen) which was Tarzan, soundtrack that won a Gloden Globe and Oscar too.
The film is name Vaiana in most european countries, not only because of brandmark but also because the woman in french polynesia (which consist of all the islands in the pacific) are famously called "Vahiné".