The question is how similar is the difficulty of the shot from the hardpan to sand, rough or fairway? Many golfers consider hardpan a very good lie and labeling it as fairway would make sense. Others might consider it closer to sand. Sand is more difficult than fairway because the sand might be soft, there might be a lip to clear, etc. I’d say it should be either fairway or sand, depending on your judgment. As with recovery, labeling a shot from the hardpan as “fairway” would say that the previous shot was a good one, while labeling as “sand” would say that the previous shot wasn’t quite as good (and it depends on how you view the difficulty of the shot from the hardpan).