This is actually a more detailed expansion of a discussion thread we discussed earlier last year, Red Moon Spring. I am really sad that it wasn’t expanded on or received any response since my reply to it, but this lays out a lot of very good options and I couldn’t agree more. I don’t know if you are aware of this but a few years back I believe it was due to a bug with red moon springs, but it had to be closed down for maintenance, or for some reason was replaced by an alternative method of fossil recruit where, for a brief time we exchanged fossils for eggs outside HC, this was if I remember correctly during or/and shortly after (my memory is fuzzy) holiday palace. This was actually a very enjoyable alternative to red moon springs, and I think combined with your idea of a dungeon similar to cliff-side where you obtain an item similar to engraved tablet would be much more enjoyable, but still fair and challenging, I believe they should be put in a dungeon that should be further scaled up too if you ask my personal opinion if we are talking about a different dungeon there is a massive power gap between loch lenile and TC, and especially if we are talking a permanent unlock, I think it should be a difficult dungeon, maybe something like MP in TC? or if it’s still consumable dungeon maybe something on par with DD or Mt. Moon, that’s less time-consuming to repeat than TC, although not as easy to repeat (but not as annoying as SR hunting) as Loch Lenile.
Fossils were put in Loch Lenile when the average player strength was much lower than it is today, conditions in general have changed massively, and there are more fossils available and in circulation, having it moved is a very reasonable demand, changes will be needed to be made to adapt and fit the new fossils in generation 8 anyway.