It is hard to tell from the mock-up, but could you turn the table the other direction, so by putting the chandy to the left of the soffit a bit more it would be centered? Or, could you go with a round table, which would perhaps achieve the same thing? The other thing that you could consider is actually building another soffit that comes out at a right angle to the existing one, and matches the proportion of the table. Then put pendants or try the chandy in that scenario - make the soffit part of the design of the dining area.

It would be quite easy to add a screen of some type behind the TV to hide electronics and make it look finished in the hallway. Lots of products out there. I think that is a better place for the TV than above the chimney and it might not be even safe above the chimney area. The pipe probably runs from the center of the fireplace up that right side of the build out. I would leave the area above the opening toward the ceiling open, but close the back of the area for the TV off, then you probably need to create a grommet in the top of that shelf to drop down cables and wires for the TV and perhaps some speaker wires? Not sure what you have. If you go to Home Depot or Lowe's you can go to their lumber area and see what panels could be used to close that off with something decorative.

You have enough room for two three seat sofas and a couple of smaller scale arm chairs. Take a look at the below diagram to see if it's something that would appeal to you. It's got two eight foot sofas and a large area rug that defines the entire seating area. One sofa is served by cubed coffee tables, the other by a larger table with an ottoman underneath for casual extra seating. See below example. If the arrangement will work for you, get some blue painters tape and map out the furniture on the floor to make sure the sizing will fit.

You don't really need a coffee table, since you have the side tables. Just tuck a c table under the side of the couch where there is none. That should free up some space. Since you want to put a unit where the chairs are, the chairs will have to be relocated. Even with your two couches and chairs, you only have eight seats. Add more with poofs or ottomans. Relocate the two chairs in front of the fireplace (with their backs to the fireplace). Or as suggested, move the couch that's in front of the window to face the other couch. Then the chairs can go in front of the window. I agree with art going around the tv.