To second RobJarvis's answer, and as I already indicated in a previous answer to a related question, there is evidence from the arena of demon possession and exorcism suggesting that demonic spirits can sometimes manifest through Xenoglossy in possessed individuals. I'm copy-pasting the relevant portion of my previous answer below:
Another source of similar kinds of anecdotes is found in the arena of exorcisms. In the preface of his book Demonic Foes: My Twenty-Five Years as a Psychiatrist Investigating Possessions, Diabolic Attacks, and the Paranormal, Dr. Richard Gallagher shares the following:
The world’s leading psychiatric authority on demonic possession delves into the hidden world of exorcisms and his own transformation from cynic to believer over the course of his twenty-five-year career.
Successful New York psychiatrist Richard Gallagher was skeptical yet intrigued when a hard-nosed, no-nonsense Catholic priest asked him to examine a woman for a possible exorcism. Meeting her, Gallagher was astonished. The woman’s behavior defied logic. In an instant, she could pinpoint a person’s secret weaknesses. She knew how individuals she’d never known had died, including Gallagher’s own mother, who passed away after a lengthy battle with ovarian cancer. She spoke fluently in multiple languages, including Latin—but only when she was in a trance.
This was not psychosis, Gallagher concluded. It was, in his scientific estimation, what could only be describe as paranormal ability. The woman wasn’t mentally disturbed—she was possessed. This remarkable case was the first of many that Gallagher would encounter. Sought after today by leaders of all faiths—ministers, priests, rabbis and imams, Gallagher has spent a quarter-century studying demonic activity and exorcisms throughout history and has witnessed more cases than any other psychiatrist in the world today.
In this eerie and enthralling book, Gallagher chronicles his most famous cases for the first time, including:
A professional who claimed her spiritualist mother had “assigned” her a spirit who “turned on her.”
A petite woman—”90 pounds soaking wet”—who threw a 200-pound Lutheran deacon across the room to the horror of onlookers in a church hall;
And “Julia,” the so-called Satanic queen and self-described witch, who exhibited “the most harrowing” case, a “once-in-a-century” possession.
Going beyond horror movies and novels, Demonic Foes takes you deep into this hidden world, sharing in full details of these true-life tales of demonic possession.
In an article titled "Psychiatrist believes demonic possession and exorcism is real" (link), Dr. Richard Gallagher is reported to have said the following as well:
He's heard the voices speak in ancient Greek. He's heard them speak in Latin. Dr Richard Gallagher says they converse in Chinese, Spanish, French; that they're wildly smart and manipulative.
The voices and the languages come out of people, he says, but they're not actually human.
They're demons. They're real, and so is evil, he says. Demonic possession exists, and he has seen it firsthand.
One could argue that, if demons are causing people to do xenoglossy today, the Holy Spirit should be more than capable as well (just like He was at Pentecost, in Acts 2).
