Treasure maps not helping

You basically have two options:

1. Improve the perception of your character(s) until the mound appears. For treasures, it's a higher threshold than other spots you can dig at.

2. Just perform the dig where you think the treasure is, if you're in the right spot, the chest should just pop out. The maps give you a pretty good idea of where it is, so you can just perform the shovel action in the area you believe it is in.

   2a. If you don't care, you can always look up the exact locations of all the treasures to dig in the right spot. (Google the map and you'll find pictures, videos, etc on how to/where to get the treasures)

I typically guessed with shoveling until the treasure showed up. On occasion, my perception was high enough to reveal the location.

You need high wits to raise it. You can temporarily raise wits with 'Peace of Mind' (skill or scroll).
Here's a thread that discusses the same approach.

Note that some treasures aren't chests such as

the ruby under a dirt pile.