Was just curious if robotics/autonomy engineers working on FSD had a chance to lobby transportation / traffic civil engineers to tweak design roads, signs, road markings or other factors to improve FSD accuracy and safety, what would they be ?

What a silly idea. Technology moves 20x faster than the legislature. There is no point in even trying this. By the time any suggestions would get implemented and (all?) signs replaced, they would already no longer be necessary -- like, 15 years past being necessary.