IIRC, there was a Star Wars novel (A Zahn written work) where Wookies actually can speak, it's just that Chewbacca has a speech impediment. Hence, his growling and hooting.I felt like Lando also understood Wookie. Am I wrong?
I'm sure that regular humans don't have the vocal capacity to talk Wookie for any length of time, though.
It was the other way around. Leia could only understand Ralra because *he* had a speech impediment.