I meant it wasn't easy. But it was. I was just making it difficult when I didn't need to. It will work fine in multiplayer.
Here is the file you need:
Hidden TreasureYou can find it in MEDIA/LEVELSETS/PROPS. It's called 'Hidden Treasure'.
You need to change a few things:

First, you need to modify the 'Luck Check' widget
--Change CHARACTER STRENGTH to your LUCK STAT
--Change the FLOAT to the desired value. This is the minimum LUCK the character needs. If they have at least this much luck they will always find this hidden treasure spot.

Next, modify the layout link which I've called 'standard treasure chest'
--Link it to your buried treasure layout. You can use a layout link and change the file reference, this is easy. Or you can remove the layout link and paste the layout components of your buried treasure directly, but this is more work. If you do this, put your buried treasure in a folder here.

If you remove the layout link, you'll need to change the logic
--In my logic, you'll see a link between 'evaluated true' and 'enable and show'. A folder will only have 'show'.

Voila. You can save different difficulties and different qualities of chest and make them different layout links for easy use. If you have any questions, lemme know!