This story is merely a dramatic example of a common lie told by Pentecostal missionaries: that they can communicate with people who do not speak the same language by speaking to them in tongues.
In fact, despite having spent nearly five years among missionaries in various countries, I have never been able to verify a single account of someone successfully using tongues to communicate. Pentecostal missionaries (if they are any good) go to language school just like missionaries from any other denomination in order to successfully preach to their target population.
So why is this story so popular? The truth is that many Pentecostal missionaries are under a great deal of financial pressure. Most promises of financial support never materialize and the support that they do receive usually dwindles the longer that they are away from their home church. Every few years, they must return to the United States and travel from church to church pleading for more money in order to keep their ministry going. However, most Pentecostals are not particularly impressed with mundane ministries that run schools, orphanages, and Bible studies. They want to hear about miracles. When a missionary claims that great signs and wonders are taking place, the money really starts flowing.
Another observation that I made during my years overseas is that there are some missionaries who are really rather lazy. The UPCI missionary couple that I knew in South Korea scarcely ever socialized with Koreans at all. They mostly just befriended other Americans and held Bible studies for other missionaries and some US soldiers stationed in Korea. In situations like this, many missionaries fail to ever learn the local language at all. This is, of course, rather embarrassing to admit when they are doing fund-raising tours back in the United States.
Based on my experiences, I believe that most of the "preaching in tongues" stories probably originated when lazy missionaries who had failed to learn the learn the language of their target population were asked how they managed to preach to the local population when they didn't speak the language. What better excuse than "I just speak to them in tongues, and they understand me!"