To be fair, OpenSpace's lighting can be pretty difficult to recreate. It has a ton of weird light types that I haven't seen used in many engines (then again, I'm not familiar with that many engines).
Lights in OpenSpace aren't designed to be realistic light simulations, but are instead art tools: For example, "alpha lights" that absorb alpha on transparent objects (this is how water is faded out near walls, or how Rayman disappears when he walks into the void at the end of the Sanctuary of Water and Ice 1). Or "painting lights", which just paint a color on an object regardless of whether that object is facing the light or not.
Also, lights only apply to specific sectors -- for example, put a platform into a separate sector, add a green painting light that's only applied to that sector, and you have a green platform. You can also set flags for whether they should be applied to objects, the environment, or both.
For Raymap I couldn't use the proper (but limited) Unity lighting system to emulate the OpenSpace lights, and had to pass the lights as data to the shaders instead.