What is the timber thing doing in a square around the fireplace area, makes zero sense to me and can it be removed.

I agree...........if it's possible, remove the surface mounted timbers from the face of the fireplace.

The clock is too brown, too much of the same thing. I pasted some ideas. You need to get some height and interest on the wall.

I have a similar large stone fireplace I suggest removing clock. On the mantle I would like to see chunky cream candles of varying heights and a floral arrangement of perhaps sunflowers in a cream pitcher. Also place or mount a tool set off to the side of the fireplace opening. Instead of drawing the eye up bring it to the focal point which is the hearth. An assortment of pumpkins can go on the hearth but with so much stone I think less is more it is stunning and I'm not sure why the frame it may be to hide where the stones collide. Interestingly enough it is easy for a mason to remove and replace the face of the fireplace. Although that might stress your budget. That may be your best bet if this becomes a design dilemma. You can start fresh. good luck