Something that I would like being added is the option to revisit quest areas that have missable loot or encounters, within reason of curse.
I think this would be a nice quality of life addition to the game, because I recently found out that I had missed the opportunity to get the Jade Tear and combine it with the Ring of Fate. This was something I found out a while after completing "The Ring of Fate" quest when I was checking through gear on the wiki. Normally this could be avoided by keeping a save file for every quest/unique encounter so you can go back, fully explore, and try out every option. But not every one plays like that or want to have that many save files for each playthrough.
In terms of implementing this option, it wouldn't make much sence to be able to go back to areas that end up collapsing or becoming otherwise inaccessible to the player lore wise. An idea for those cases would be to add rare encounters of treasure hunters were you can either fight for their rare findings or buy the item for an expected greedy price like a hostile version of Gianna's Caravan. Alternatively, we could have an "expedition" service added to the Wayfort where the player pays to have Daliza organize a team to gather resources for a couple days with the chanse of finding items and missed loot. Or just add a chance for enemies in that area to have a one time drop of the missed item.
As for missed encounters, I think the easiest way would be to just add them as a one time rare encounter near the quest location if it's one that makes sense being inaccessible with maybe some added dialogue about barely getting out in time, or not getting the chance/missing to face the player last time they where there.