I never understood the English Only movement too well. It’s not as if we are in danger of waking up in a Kafka-esque scenario unable to communicate with anyone because Mexicans took over the entire country overnight. At worse we will have to deal with dual language “wet floor” signs and more Spanish language radio stations. Probably an increase in Mexican restaurants, but I don’t consider that a bad thing.
About Glossolalia: some linguists actually bothered to study these people and figured out a scientific way to say “they are blathering idiots.” It turns out that people in different countries all speak in tongues differently based on random fragments of their native language. Imagine all the other things they could have done with their time.