When I was in college in Los Angeles.....decades ago.....I heard the story of what happened in the campus chapel (at Loyola Marymount University).
A student started speaking in tongues in front of everyone.
After the mass, an elderly couple approached the student.
They had come to America when they were young, and they told the student that he was speaking an obscure dialect spoken in only a remote area of Russia. They student had never been there. I wish someone had asked the couple to translate the speaking into English.
In a religion class I took as an elective, a male student was speaking in tongues one day. Of course I didn’t understand what he was saying, but it was unusual to say the least.
a male student was speaking in tongues one day. Of course
I didn’t understand what he was saying
***
Sometimes someone else will respond with an interpretation.
I wish someone had asked the couple to translate the speaking into English.
This phenomenon has also been known to happen to people after a head injury or coma, indicating that it is a possible capacity of the human brain in some instances.
As someone who has studied six languages and remains fairly fluent in a few, I listen with skepticism on most of the "tongues"-speaking I have heard when visiting pentacostal churches. It all sounds the same, like nonsense syllables with no syntax. But from your description, this young man was manifesting what was described in the Bible -- an ability to communicate in a previously unstudied language for the purpose of evangelizing.