Looks like the trim has recently been painted. Will the wall stay the same color - it looks gray in one pic and gray green in second pic, on my screen. Knowing wall color is best place to start. Also, can you share something about other colors you'll be using, drapes, sofa, etc.
Thanks.

I don't understand what you are using that precludes white or light colors, because I would have painted it the same as your wainscot. Gray or charcoal?

Brown Leather couch

Oh, I'd paint it the color of the wainscot and trim.

If we use for place and it's white like trim then soot will show badly. Right?

I would go with a deep chocolate brown; white and light colored fireplaces will get dirty/smoke stains over time. Hope that helps!

Remove the paint to expose the brick. Probably by sandblasting. That's the only thing that will make that particular "functionally" designed fireplace fit into you rather formal room. Second choice would be a flat "whitewashed" white. Put some slate or sandstone on the hearth.