Yes, I am fine with site_type -> archaeological_site and if you see any more please feel free to change. (IMHO change is a bit silly and retrograde but consensus and conformability are more important).

More generally, I trying to find a way to find to succinctly classify historic POIs. The historic tag itself gives a sense of "how interesting is this?" which I think is good archealogical_site (may be nothing visible or just a grass knoll) vs. (possibly more exciting) ruins for example. Then there is the historic category itself, which is sometimes covered by the "historic" tag itself and sometimes not. Still experimenting and have not found the perfect answer.