Howsabout Nien Nub's dialogue, pitched down and cut and pasted a little? It's a real African language I believe, maybe more samples could be tracked down? It's already a "Star Wars language" and more obscure than Japanese. Might be good for a sentence here, a word there, but this is assuming you want the gungans (or nemodians?) to say as little as humanly possible in the new cut. Which would be swell! Also, there's text-to-speech synthesizers (for blind people) on the internet you can use for free. Figure out the sentence you want to say in English, get a language dictionary and translate it into whatever language you decide on, and type it in. Then you can save it as quicktime file. They have a range of voice types too.