Could implementing things this way cause a problem if another script also post-processed your pages? Could you wind up in a loop where each script kept modifying the page in response to the changes made by the other script?
Technically, it's possible. To get stuck in a loop you'd have to have another script that uses MutationObserver to reverse the changes that Localize.js makes to the DOM. We haven't run in to this yet, but I'll see if there's a way to safeguard against this.