You mentioned Acts earlier, and I’d like to add that there were no incidences in the Bible that depict the apostles speaking in tongues that they couldn’t comprehend.

EDIT: I’ve also heard it argued that the gift of tongues was only one that people had as a sign to unbelievers in the time before the completion of the scriptural writings.

EDIT PART 2, EDIT HARDER: Also, nowhere in the Bible is the concept of a “spirit language” encouraged or discussed.

EDIT 3, EDIT WITH A VENGEANCE: I guess my main question is what benefit could there possibly be to not understanding what you’re saying? In theory, you could be saying something really awful without your knowledge?