That said, listening to the actual audio that's replaced the alien speech is pretty grating after a while. At times the reversed foreign language tracks are pretty apparent for what they are, and it takes you out of the experience when you're hearing snippets of spanish. Also, the reversed lines clip off at the end in a way that just doesn't happen with ANY sort of speech. I assume it's just because some sentences start with hard consonants, and so when they're reversed they just end abruptly. If it were one alien race that had this problem, that'd be one thing, but after hearing it for an hour from both gungans and neimoidians, it's pretty annoying.
Also, because of the sheer amount of alien dialogue that your re-write requires, suddenly everyone in the movie seems like an expert in alien languages, answering races they've never met as if they were speaking English. Part of what was cool about Han speaking wookie was that you knew it was rare for a human to do... sort of similar with Anakin speaking Huttese. This isn't a huge deal though.
What I'd suggest is scrapping the sounds you currently have in place for the gungans and neimoidians entirely. Either find some new audio source (a la Burtt creating the Wookie language) or, and this will sound crazy, I know, get some actorly types and actually re-record the dialogue in a less annoying fashion than Lucas's version provided. You could either create an alien dialect this way, or just have it done in english with new character interpretations. I must admit a long-standing desire for the neimoidians to speak with British accents. I figured it would bridge them to the bumbling, second-tier imperials from the original trilogy, and it made sense to me that these creatures that longed to be in the good graces of Sidious's coming empire would learn to affect the coming Imperial tongue. Maybe that's a crazy idea, but hey.
I was eager to see what you were going to do with the two-headed announcer, and was sort of let down to hear the German track used for the Greg Proops part. Granted, I hate the Proops performance, but it's so obviously just the German track laid in there.
That said, your version of the pod race is f-ing PHENOMENAL! I was shocked and amazed at how thrilling it became once it was edited down and accentuated the clips from the dvd that focus on Anakin's intelligence rather than dull, pretty shots of racing in a desert. My favorite part.
Again, the script changes are really smart. With some more work, I think this can be hewn into something great. And if you ever need any help, I offer my services in any capacity you would need.