That's part of my point--not a known earthly language but-- A heavenly language.
However, a close friend of mine . . . with a Native American ancestry on one side of her family . . . and a heart for the tribal groups of all Native Americans . . . was once on a missionary type visit to several Northwestern tribes.
At the end of the service, often, IIRC, standing around in a loose cluster of folks . . . all praying together out loud . . .
IN THREE SPECIFIC DIFFERENT CASES WITH THREE DIFFERENT TRIBES OF THREE DIFFERENT LANGUAGES . . . after the closing prayer time of praying out loud together . . . an old member of each tribe would turn to her and ask her where she had learned the ancient more eloquent version of their language--AND WHAT A BEAUTIFUL SUMMARY OF THE GOSPEL STORY SHE'D JUST SPOKEN OUT DURING THE PRAYER TIME.
She'd had no awareness she was doing so. She was just "praying in tongues" as usual. She was rather stunned by the 3rd time on the same trip.
In my initial tongues experiences . . . there tended to be lots of "holy Spirit goosebumps." Over time, the walk by faith vs feelings became the priority.
I fussed about such to The Lord several times and He finally seemed to have enough of my fussing and asked me if Salvation was by faith or feelings. Faith, of course. H noted that tongues were Biblical. And exhorted me to continue praying in tongues in faith AND TRUST HIM THAT HOLY SPIRIT WAS CONVEYING THE PERFECT MEANING TO HIM REGARDLESS OF THE 'GIBBERISH' SOUND OF MY VOICE.
I've done so and God has continue to confirm such from time to time with His special blessings and touches. But most of the time, it's a walk of FAITH. Who'd a thunk! /sar
I've never observed that Holy Spirit cares very much for our silly private interpretations; doctrines of man and certainly not the doctrines of demons that parade as truly truest true truth in so many groups--seemingly particularly naysaying groups.