You, sir, may have just made the most useful third party plugin I have seen yet. Construct should distribute with this.
D/ling now, will give feedback.
My two sense on the raw data: try to make this plugin nothing more than an interface to the Wiimote. if the Wiimote returns rough data, then pass back unadultered rough data. Let it be a limitation of the Wiimote, not an issue with your plugin. And if you must provide some method to smooth it, also provide some way to turn it off
EDIT: My vote is for one object that manages all plugins, then I can dynamically modify things to multiple controllers more fluently. Also, you could do things like reassign controller numbers in-game.