To the end, Nim's largely prompted and cursory sign use seems never to have expressed anything particularly meaningful. Project Nim was a total bust: quixotic, constantly improvised, and badly managed. I'm not sure it should be called a project at all.
Yes, it would be wonderful to see propositional communication across a interspecies barrier. But that hasn't happened yet. This film should convince you of that.
And it should also convince you that the title of Herb Terrace's 1987 book Nim, A Chimpanzee Who Learned Sign Language is blatantly dishonest. I guess the publisher would not have gone with an honest one like "Nim, A Chimpanzee Who, Like Every Other Chimpanzee, Never Learned Sign Language".