My concern is that if it's documents or books and they're in a foreign language, the heirs won't know what they are and may just toss them.

WSJ: He Drills for Answers | Robert M. Edsel | Cultural Conversation by Joanne Kaufman

We learn a foreign language by actually speaking it as much as possible, not by reading books and absorbing theories.

FORBES: Why Apprenticeships Are the Fastest Way to Acquire Skills