The Jews at pentecost had come together. They were spread out and many lived in other countries, and they spoke and understood other languages, italian, greek, french, whatever the case may have been. The Holy Spirit allowed those diverse language groups to understand what was being said & for others to understand them. Nothing more, nothing less.
Why would an all knowing, all powerful, very logical God, who is not the author of confusion as per the bible, use and promote unintelligible gibberish?
I am not LDS. I'm not sure what bible they use. Do they allow blacks to become LDS these days? That was an issue for them back in the day. Maybe it has changed.