I’d consider replacing the Era 100s with something larger for that big room. I’d go with Fives but 300s would likely do as well. Maybe relocate the one by the table to on top of the kitchen cabinets so both areas get better sound and it is more even across the table’s seats?

Don’t get locked into the sub’s proposed location, far better to try several and pick the best sounding one you can live with it located at.