I have a close friend who was speaking "gibberish" has you called it, in a prayer meeting, and found himself speaking in a Ghanaian visitor's own village dialect. All he was doing was speaking in tongues in exactly the same way that Pentecostals do, but on this occasion it was an understandable language. But it was a one-off for that particular situation.
I had the same experience praying in tongues, and a New Zealand lady told me that God spoke encouraging things to her through me in the Maori language. I had no idea that I was speaking Maori, a language I had never learned at that time.
To my understanding ... That ^ was exactly the point of the Holy Spirit putting words in the mouth of the Disciples...a foreign speaker in the crowd could understand the speaker.
Now this woman you mention had duel language? English and Maori?