Someone already mentioned that Chewbacca could be somewhat understood in the Star Wars universe. That's an objective fact.
Is it? In the onscreen version of that universe, Chewbacca doesn't really deliver any information to his fellow adventurers through his growls - except when pointing at a warning light on the
Falcon's control panel at the same time, or suggestively waving a gun, etc. Sure, the heroes "answer" as if they understood what Chewbacca said, but the various handlers of Lassie did that a lot, too. Doesn't mean there'd be intelligence at both ends of the conversation.