In the last variant I changed the word "returning" to "traveling." If you say returning, the question is from where. Well, you can say she's returning from Naboo...but why would you say returning? Did she recently leave and now she is coming back? Or is Coruscant her home? See, it doesn't make as much sense to say returning or returns. TM did have "en route," and while it conveys the idea, I agree that it is a bit clumsy to use in a title crawl.
I just looked at the official ep. II crawl and it does the same thing with the word "returning;" it isn't given any sort of context. I thought I remembered seeing the official crawl saying something about Padme returning for the first time in ten years, but after I looked at it I realized I was thinking of the Clone War by MagnoliaFan. He was first person to use the word "returning" and have it actually mean something!