Art you love. Look at local galleries or sites such as minted.com

I would place two chairs on either side of the cabinet and then find two larger pictures or stack some smaller pictures. I think something simple and graphic could work. I would then move the armchair at the head of the table to sit beside the window with a small table and spread the chairs at the table out.

Is it possible to have the light fixture moved so it is centered on the table and built in?

The symmetry you add to the built-in wall with art, chairs, etc. will call attention to the light fixture not being centered.