Hello Meister! It's truly an honor to have the creator of Palpus X: Annihilation as a customer :D
Is this negative effect probably happening because of the normalized blend mode? I recommend using the "multiply" mode with renderer.SetLightsBlendmode(0). You can also try using "Multiply LDR" if you're using HDR, to create a "clamp" on the pixels.
Another thing that might be happening is that the overall light intensity is too high. You can reduce it to 1 using the renderer.SetLightsCompensation(1) function. By default it is currently 3.
And you could also disable the HDR of lights by using .SetLightsHDREnable(false)