I’ve accounted for light, condition and the broad location, but the area definition and outdoor-space rights still look too uncertain for a single figure. I’d show a range instead: confirmed usable space, a close micro-location match and practical private outdoor space would move the villa...
A compact contribution format might help: observation date; neighbourhood; property type; asking-price band; first-seen date; latest-seen date; status; and link where available. Contributors could add notes, but those fixed fields would make later comparisons less subjective.
A simple approach is three groups: still active, confirmed completed, and outcome unknown. Keep withdrawn stock in the unknown group unless you can verify what happened. Then calculate the 74-day measure only for the category it actually describes.