More training and recovery time would certainly be beneficial (you could see the lack of it here), however, I think they also really need another competition under their belts before worlds.
I don't think they will change it, I just think they should (actually, I think they should have changed it earlier is the season so they'd be refining it by now). They're scoring well enough with it that I'm not sure their team has recognized what a problem it is, and how much it could hold them back this season.
Zach is not goofy enough for Austin Powers. You need a kind of wink, wink, nudge, nudge with the audience to pull it off that Zach does not have. And then the disco music they've chosen is all kinds of blah and dull, plus everyone and their dog is doing disco. Even here, at Canadians, I thought it was choreographically and in theme the weakest of the top four dances. Their skill still puts them in the mix internationally, but this is not the program to wow the judges into putting them on the podium, in my opinion. They needed something that stood out more, like Piper and Paul have.