Having put some more thought into how re-imagined Gungans ought to sound, and for some reason my mind kept wandering back to the rather silly idea that they could have accents that sound reminiscent of Celtic-- like if a celtic version of Jim Varney was playing Captain Ahab, that would be Jar Jar's voice. It sounds wacky, but in my head it works. In the car today, I found myself reciting a bunch of Jar Jar's lines in various different voices and accents, and the one that seemed to sound the best to me ended up being a vague derivative of Scottish.