SPEAKING IN TONGUES

Demona cast a spell out of the Grimorum Arcanorum the night before the final stone of the castle was set into place to break/complete the sleeping spell on the gargoyles. The spell she read over the gargoyle statues was a language acquisition spell, so the gargoyles would awaken speaking 20th-century English instead of 10th-century Scottish Gaelic. The spell worked on all of them, but was most effective on younger and more malleable minds, for the same reasons that youngsters usually catch onto learning a foreign language faster than their elders. This explains why the Trio were able to instantly grasp so many idiomatic phrases and slang terms that glided right over Goliath and Hudson's heads.

When Avalon sends a person or people to 'where they need to be' via one of its magical skiffs, a language acquisition spell is bestowed upon the skiff riders: they will find themselves able to fluently speak the dominant language of whatever land they are sent to. This explains why Goliath, Elisa and Angela had no problems getting around Guatemala, Japan, Prague, etc. (English may be a popular second language to learn in foreign schools, but not that popular.)

The spell takes effect subconsciously; the skiff rider will not even realize he/she is speaking a foreign language unless he/she tries to express a concept that the new language has no word for. The spell remains in effect as long as they stay in that land, but dissipates (and the language skills acquired with it) once they move on. Once Avalon has finished with leading people around by the prow, to coin a phrase, the submerging of the skiff will make the last application of the spell permanent. The riders have a parting gift, whether or not they ever realize it.