It looks fine. Black is SEVERE looking and looks DUSTY all the time. As in ALL THE TIME! A low gloss black looks dusty because it is low gloss. A high-gloss black looks dusty because you can SEE the dust...Every gloss level of black looks dusty. Every day. All day. The beauty of neutral coloured stone with a bit of movement is: you can't tell if they are dusty/dirty or not. And that is a major blessing. Finish the surround in the stone tile you have picked and enjoy your new space. You will be happy you did. Just relax. You've done a fine job.

Where is it going, what else is in the space ? You do not decide colors in a vacuum.

I don't think shutters will look right on the style of that house. Instead would you consider improving your landscaping between the trees and the garage? I think adding some color, texture, and height would help add some liveliness.

The long panels will be half hidden by your sofa! If you have an alternate arrangement possibility? That would get you a different answer. Existing arrangement ? flatly NO, A WASTE OF MONEY TO GET A SAWED OFF RESULT. Invest in quality shades with light control versatility and good looks. Going for something else? Move the sofa!!!