in fact I redid part of the last "fix", making it working properly now.
Before we were changing Lamp->la . This is the Blender Lamp, we shouldn't touch it.
So this part of the code is correct now.
Things that could be tackled:
- color attribute is returning negative values when NEGATIVE is toggled
- objects with no material (default gray one) still don't support lamp spots (not spot lamp but the spot of the lamps)