My inclination is to expand the definition to "Untranslated foreign language is used, in a way that means that only someone who knows that language will understand what has been said."
So a if character identified as French or French-speaking says "Merci" to someone else who's just handed them something isn't a Bilingual Bonus — even if you know virtually no French, you can guess that it means "Thank You". Not just a vague "That was probably something nice" but "Oh, they said 'Thank you'."
By contrast, in this exchange between two characters in Margin Play
"Got anything else to say?" His voice was hot.
"Yeah," I said. "You hit like a pidoras
the context makes it clear that what was being said wasn't friendly or nice, but only someone with more than a passing acquaintance with Russian (or a translator program/site that does Russian slang and invective) will know what a pidoras
is and why he reacts the way he does. It is a Bilingual Bonus
. People who are Bilingual
— Russian in this case — get a bonus
bit out of the scene that people who don't, won't.
edited 23rd Sep '13 3:40:45 PM by Madrugada
...if you don’t love you’re dead, and if you do, they’ll kill you for it.