a) I think "Simulacrum Levels 1 - 4" are terrible names and we should be looking to replace them, generally.
b) usually, there's not really a good reason to bring "simulacrum" into it. The concept of simulacrum levels makes sense when you're talking about how how relations-to-reality change over time, or how people relate to it in different ways. But I don't think it makes sense to bring it up every time the distinction between physical/objective-level reality and social reality. Social Reality is a perfectly good name that I think is at least relatively transparent about what it means.
This mild rant brought to you by this comment which was one-straw-too-many for me.