Make a new site for each locale and synchronize their page structures. You could also create machine translated versions using this script (although they would need fixing by a native speaker):
function localizepagestolocalizedsites() {
var fromblog = SitesApp.getPageByUrl("https://sites.google.com/a/yourdomain.com/english/home");
var toblog = SitesApp.getPageByUrl("https://sites.google.com/a/yourdomain.com/japanese/home");
var nextbloc = 0;
while (true) {
var pages = fromblog.getAllDescendants({"start":nextbloc,"max":100});
if (pages.length > 0){
Logger.log("starting at.."+nextbloc+" there are .."+pages.length+" pages starting with.."+pages[0].getTitle());
var i = nextbloc;
for (var x in pages) {
var localizedTitle = LanguageApp.translate(pages[x].getTitle(), "en", "ja");
var localizedBody = LanguageApp.translate(pages[x].getHtmlContent(), "en", "ja");
toblog.createWebPage(localizedTitle, pages[x].getName(), localizedBody);
i = i + 1;
}
} else {
break;
}
nextbloc = nextbloc + 100;
}
}