I think the changes you describe don't necessarily reflect an evolution or change in the spirits themselves. If, for example, one believes that spirits are generally very old and very wise, the fact that they offer information about present-day technology doesn't mean they learned something new in the last 10 or 100 years. It could just mean they would provide relevant, rather than seemingly fantasical, information to people of any era. It wouldn't help you if a spirit told you how to make a better mud-pack to reduce swelling, for instance, nor which brand of medical nanites to avoid. That information isn't relevant today. But they might well talk about medical techniques and decisions that are real options for you.
I'm not saying spirits don't evolve. I think they gradually learn and grow like any other being, probably on a much longer arc than mortal creatures do. But it's worth recognizing there are so many other interpretations. Anything we say about spirits is so speculative it's almost like playing an imagination game.
@altmagic I agree and that actually was my point in writing the post. Any description offered on spirits by a human is ultimately going to be filtered through human experience and perceptions. So there is a lot of speculation there.