i was at a linguistics olympiad once during highschool and there was a task regarding some malayic language and yeah the fact that i knew two indonesian words and that repeating word-word twice makes it plural was a big starting boost, instead of guessing what it is and then proving it i could just assume it as true and move onwards. obviously, this isn't exactly real life linguistics but it really turned it from just a hard puzzle to a hard puzzle but you get a bonus if you know about obscure languages (malayic languages aren't that obscure, they're actually super common, but you get the idea, i hope). so not even fluent can help i guess