By returning from apple script the original widget is not changed, only the displayed stuff. This approach only allows to update the things that are listed in the configuration view.
However using the update_trigger method you can change anything, there is no limit to what you can change.
For an example e.g. have a look here: update_trigger removes uuid of target...
Or the docs for the update_trigger method: http://docs.bettertouchtool.net/docs/apple_script.html