I'm pretty sure Greedo and/or Jabba were speaking Quechua, just with gibberish sentences. Similar with Lando's copilot in Jedi (I think one of his lines translates as "A thousand herds of elephants are on my foot.")

About 10 years ago Ben Burtt did this novelty pocket-sized phrasebook with short translations for Star Wars languages (like Huttese and Bocce), but from what I can tell they're either original material for the book or transcribed from the screen. I think he said a few short phrases in the movies were his, but that they were mostly mangled human languages. Like it's been mentioned, nothing to combat Tolkien or Marc Okrand.