I think it's great that you can spy on your war opponent's Museum artifacts benefits once you have finished those 3 spy reports in Harriett Tubman in University. I think you should be able to see your war team members Library, University and Museum benefits. This will help the war team in defense planning, such as alliance troops and stronghold troops for defending war bases. Besides, you are on the same war team and in the same alliance. I am not sure what adverse effect that would have on the alliance or alliance war team. It may even encourage allies to prioritize certain benefits to research or to get.