How is "Chult" pronounced? Is it /tʃʌlt/ or /tʃʊlt/ in IPA?
Chult, as pronounced by Wizards of the Coast employees, rhymes with cult. I believe the IPA would be [tʃʌlt]. You can hear WotC employees talk about Chult on almost every Dragon Talk podcast from March 30, 2017 through today anywhere you find podcasts or on the D&D website. This one has a segment about Chult starting at 7 minutes in.
See this video.
It is pronounced [tʃʌlt] by Chris Perkins