Its a happy moments that with your efforts all the bugs are removed so-far.
Except one thing:
When I export kml file from your plugin, and import it into Google Earth its working (without WMS support)whereas if I import leaflet kml file for instance in WordPress plugin scribble map (http://scribblemaps.com/) plugin available at (http://wordpress.org/extend/plugins/scribble-maps-kml-embed/), its not working.
My question is, Are you using different standards of making kml inside leaflet and/or scribble map developer using different standard.
Kml should work with every scenario (either I am importing into Google earth/Google map or scribble map)
Could you brief little bit about it.