From my perspective, there haven't been enough big sci-fi plots with polyglots in them, and why should there be? In sci-fi worlds, you can invent translating fish that live in the ear canal, protocol droids that know 6 million languages, or pan-galactic English. But Sam Roberts' op-ed in the NYT, "What do you say to an alien?" is a perfect set-up for a polyglot sci-fi plotline.
Roberts goes on a quick tour of the problems that need to be considered, from what we'd use to communicate with them to what the bureaucrats say we should do, were we ever to be contacted. Roberts muses that no protocol exists, but according to Jill Tarter, the director of the Center for SETI research, a best practice for extraterrestrial communication exists.
It boils down to, if you get what looks like a signal from another civilization, then let the whole world know, but don't reply until there's been international consultation. The real challenge is to get that international consultation going before we know if anyone's out there.
But David Bellos (whose book was paired with mine in a recent review) pointed out in bigthink.com that if we ever made contact, we may not immediately recognize the systematic behaviors that constitute the alien language. Bellos also provided the big opening for the polyglot:
I think it would be fascinating if aliens did land on this planet and we had to sit down like those Jesuit missionaries in China three, four hundred years ago and just listen to them and work out what the language was. That would be a real big mind job and who knows whether it could be done or not?
In this sci-fi plot, we have some ET contact situation (something that Darren Aronofsky, say, could cook up) in which the human can't understand the aliens, of course, leading to international confusion. They're saying something, but what? No human-created AI can crack the code, so who is better for a "real big mind job" than a hyperpolyglot? And why not go with one of the best? Because this is sci-fi, the plot goes Jurassic Park: A rogue geneticist goes to dig up Giuseppe Mezzofanti's tomb for DNA to clone.
To make the plot even more complicated, let's say the tomb is empty, raided by 19th century language cultists. But who else could be cloned? My money would be on Sir Richard Francis Burton, who could learn the alien language in the unique way that Burton could. (He was famous for his brothel exploring and for taking native wives, though the latter was standard practice in British colonial India for military men.) Though Tokyo and New York City undergo their inevitable destruction, Burton averts an intergalactic crisis; inevitable happy ending.
Of course, the biggest sci-fi part of the plot isn't just the aliens, it's the cloning of a "genius." That's a post for another time, but I will echo what I say in the book: Hyperpolyglots aren't born, and they aren't made, but they're born to be made.