I think if the room itself is balanced and the light is over the table, you probably won't notice the window alignment -- one tends to read furnishings in functional groupings.

But in the end, only you know what would bug YOU.

Unsolicited comment - I think you should do something to partially block the view of what looks like your neighbors' utility stairs, and to unify your windows and French doors (the top trim doesn't line up). Those pretty windows and doors should be an asset, and right now they really aren't.

The chandelier will look fine centered about the table. Even if it is centered on the windows, that is only obvious from certain angles anyway. It won't matter. However, I would suggest planning ALL the lighting before making a final decision.

It looks like a great family space.

To me it does not look like there is enough room for a buffet the way you have shown the table pulled out. I would center the table and chandelier with the window, put the buffet in front of the window with some plants on it. I would not like looking at my neighbors ladder, toys, etc.

Put tape on the floor for the buffet measurements. You need at least 36 to 42 inches clearance between your table edge and the front of the buffet to pull out chairs and walk behind people seated.
Not ideal, but If you place a buffet in front of the window, add a cafe curtain.
https://www.houzz.com/magazine/key-measurements-for-planning-the-perfect-dining-room-stsetivw-vs~25889832

Being centered on the room and over the table is more important than on the window, especially since you say the rooms are open to each other. My thoughts! Happy decorating...