It's intriguing that it talks about very simplistic sprite definitions (8 colors), but yet seems to expect the sprites to be rendered using 3D hardware (talk of normal maps and lighting).
I agree very much with both of you. I assemble all the tiles into texture atlases (and earlier post discusses the technique) and then use a fairly simple shader to render. If you look in the gb/graphics directory [1], then you can see the GLSL code. It was originally coded for OpenGL 3.3 with geometry shaders but I switched to OpenGL 3.00 as a stepping stone to ES 2.
The whole model is based on the concept of "SNES Unbound": I want to have effectively infinite numbers of sprites with many layers and any Mode 7 effects with arbitrary scaling and rotations. This is a very small level of expectation of a modern GPU, so I can get about 1,000 FPS on my laptop with millions of sprites, because I only use a single OpenGL draw call per layer.
Anyways, I'd be happy to comment or chat more with you. Maybe I should post some screenshots of the editor.
Jay
1. https://github.com/get-bonus/get-bonus/tree/master/gb/graphi...