Some other things that can be considered:

(1) as previously mentioned, sharpen their claws (or give them visible ones) and their teeth

(2) change the color correction along the lines of APOCALYPSE NOW, with the greens, oranges and yellows (as seen in some of Vaderios' earlier work) being enhanced.

(3) do not add more SCENES with Ewoks per se but more Ewoks into the shots of the final battle to better give the impression of the storm troopers being overwhelmed (such as when they come up over the log when they first attack the storm troopers, add another line of Ewoks behind the first).

(4) would there be any way to depict the Ewoks as capable of burrowing under the ground (again, more references to Vietnam) and maybe pulling some storm troopers underneath?

(5) change their language to something more gutteral and more along the lines of how Chewbacca speaks. Definitely make their war cries more frightening.