How to create a passphrase for someone who doesn't understand English, etc

All of my older relatives don’t speak English or any other languages in which diceware word lists are available in. How do I generate a secure master password/passphrase that they could use for a password manager, etc.?

Make your own? Could help others as well in the process!

Randomly pick some words from your dictionary. And try to be really random about it/use a RNG to determine the page number etc.

What languages do they speak? Any of the ones in the bip39 word lists?