I would change the mantle. I have never seen this set up.

It’s very very dark. I wouldn’t paint the stone but I would consider using a thin whitewash on it to lighten it. The art above adds to the dark and dreary feel but assumably this is a realtor photo and the furnishings are not yours.

The mantel does look odd with the extra length on the left end. Could that mantel be removed and a more evenly proportioned one installed? The wall seems to be built out on that side - I wonder why.

It looks like the room has very rustic features so you’re right that you shouldn’t go too modern.