Come here, it's a secret. They had a non-speaking cameo when Timon and Pumbaa were searching the Elephant Graveyard and Scar's lair for a new home
(if that is the short scene you are referring to).
Overall, I was satisfied with the role of the hyenas. The hyenas' attack on the meerkat colony explains why Timon said he "hates hyenas" before he did the hula dance. Pumbaa couldn't have interacted with Shenzi, Banzai, and Ed before the battle at Pride Rock since Banzai was unfamiliar with him. Since a majority of the film's events parallels with the events of the first film, all the hyenas were plotting with Scar and then eventually lived in the Pride Lands which did not require Timon and Pumbaa's involvement until a certain lion ran off to reclaim his throne.