NO! Leave well enough alone. What’s missing is texture and color and warmth. You need a different warmer paint color and more natural materials. No silly fake “wall boxes” that bear no relationship to the formal judges paneling that they are trying to fake, badly.

The problem, as usual, is too much cold gray. With only token nods towards “warming it up”. Without a commitment to more color and warmth, you will always feel the room to be off, no matter how much cringeworthy “design” you litter it with.

I think your dining room looks great! I wouldn't add moulding. I would maybe add a rug under the table and chairs that has a little color. Something that blends with the art above your console. Your curtain panels are too long. I would shorten them to "just touching" the floor. - I'm not a pro, so you're just getting the opinion of an amateur.

That moulding doesn't go--at all!--with the MCM style of that room.

I wouldn't. What you're considering would create oddly disproportionate boxes on the wall that would look like an unnecessary DIY afterthought. Your room is already so pretty in its clean-lined simplicity.

Like the idea of painting the back wall, but the are over the console isn’t staying, I’m trying to find something for that spot, open to suggestions for a rug/artwork

I'm with the other posters - don't think the moulding will add anything. In fact, I think it will date your dining room and make it more like builder grade construction. No offense meant. Just trying to give an honest opinion. Your dining room looks quite good as it is and your photo grouping is quite successful!

Absolutely not...why would you want to gild a lily? I would add a runner on the table with a striking design to add a bit of spice, but no molding.