I don't know if it is a bug or it is intended, but red light does not emit light. Or better said, it iluminate only back and sides on short distance. Like in this picture.
https://steamhost.cn/steamcommunity_com/sharedfiles/filedetails/?id=2343814155
White light is there for comparison. Note that white light iluminate celling, but does not iluminate sides or back of light block part. With red light is oposite.

Reason why I'm asking for this feature is that I wanted to create subtle red ilumination for cockpit. To be able to see dials while not obstructing night vision.

For now, I have made workaround with iluminating cockpit from below trough small gaps in floor. Not the best solution, but at least it is better than nothing.

https://steamhost.cn/steamcommunity_com/sharedfiles/filedetails/?id=2343817603