OK, that makes sense. I mostly didn't like that there were two park objects mapped on top of each other. Based on what you said, I removed leisure=park from the Estate and retagged it as historic=estate (only 8 uses per taginfo, but I couldn't find a better historic=* tag): https://www.openstreetmap.org/changeset/166497969. I also added some additional tagging for its NRHP status. Let me know if that looks reasonable.