Start by checking out different bulbs. There are different colors of light as well as spots vs. floods, and that may solve some of the issue. You could also see what aiming the lights upward to wash the ceiling would do. That is not to say that you shouldn’t add other lighting, either lamps or hanging.

I would want larger scale chairs for this room. If you have any friends over 50, you might not want the chairs to be too low. I'd stack the 3 pieces of art vertically in the stairwell and hang new, large art on the long wall and above fireplace firebox opening. The ones in the dining room need to be lowered (centered 5' above the floor and hung one hand's breadth apart.) Would you rather look at the back fence or the fireplace? The trees outside are lovely but the fence is humdrum and utilitarian. How about using top down/bottom up shades so you can hide the fence but still see the trees up top? I think you could use a larger rug, especially if you get leggy chairs. They should sit entirely on it, while the sofa only needs the front 1/3 to 1/2 to be on the rug.

My suggestion is to paint all the walls the same color and to paint the tray ceiling a striking color which you chose from accent colors in the space.

I already have 2 end tables on each side of the room. These tables come handy for putting my computer on them, a phone, etc. I don’t have a sofa yet but I contemplating re-designing my reading and study nook. To lounge is to be a bit more sleepy and I need to be alert for my language study and writing projects.