When working on the pocketnotes to go mobile app, I ran into a problem viewing local xml files via the StageWebView component on an Android device. It turns out that special handling is involved which I found out after reading Air on Android: Displaying local web pages in StageWebView.
In essence, you have to copy your read only xml/html files from the installed .apk file on your device, which is located in the application directory, to the application storage directory.
The post has a brief explanation on how to accomplish this with a few lines of code. To make it consistent across android and ios devices, I found a blog discussing Local File Access/Editing for Android and ios.