LLMs learn to translate without explicit Rosetta stones (pairs of identical texts in different languages). I suspect they would learn to translate even in the absence of any identical texts at all. "Meaning" is no more or less than structural isomorphism, and humans tend to talk about similar things in similar ways regardless of the language used. So provided that the pendrive contained similar topics to known texts, and was large enough to extract with statistical significance the long tail of semantically meaningful relationships, then a translation could be achieved.