No, baluster spacing is not a big one. It isn't even a medium-sized one. Reread Katen's comment. There is a strong and clear message there. Don't miss the forest for the trees, folks. It doesn't matter if they were constructed or repaired in 1609, 1709, 1809, 1909, or 2009, if the spacing is too wide, you tell your client, and get on with things. Similarly, if you think that upgrading a particular receptacle to a GFI would make things safer, tell your client! If someone argues, and you think you need a dated code reference to refute your position, then you know less about homebuying, home inspecting, houses and the people who live in them than you think you do.