Tonight, the version 1.0 Beta 5 of the plug-in now shows borders around rendered tiles and brings a bug fix that could give weird results with lines (UbuntuBirdy, I hope it will resolve your issue). I also removed double faces to avoid bad results shown on the chairs in Cecilia's test file.
Enkonyito, I made some tests about area and mesh lights, and you can use some working code found in the comments of [font=courier new]YafarayRenderer[/font] constructor.
In the source code you posted, [font=courier new]corner[/font], [font=courier new]point1[/font] and [font=courier new]point2[/font] must be arrays of 3 floats not [font=courier new]Point3f[/font] instances (by the way, [font=courier new]from[/font] parameter isn't used).
You should also take care of the orientation of the triangle built from [font=courier new]corner[/font], [font=courier new]point1[/font] and [font=courier new]point2[/font] (if ever it's wrongly oriented, just swap [font=courier new]corner[/font] and [font=courier new]point1[/font]).
About mesh lights, you have to provide the integer id of the mesh used as a light in a parameter named [font=courier new]object[/font]. This id is returned by [font=courier new]startTriMesh[/font] method so you'll have to store the ids of the meshes used as lights somewhere.
Good luck! [:)]