I'd do the white perimeter and the dark wood for the island and like Jan says, wait to close before picking a backsplash. BTW Here's a pic of my kitchen with white perimeter cabinets and a dark oak island. Maybe I'm biased but I don't think it looks dated at all. In fact I think it's better than the gray which is basically at the end of its trendiness.

I think your backsplash is fine. it suits the style. that hood however, absolutely wrong! I like your plaster idea, or, consider doing one in zinc or a zinc finish. then the sconces. Something like this. You can go lighter on the vent hood https://custommetalhome.com/range-hoods/ or something in this style, but more of the zinc finish the zinc looks like this, color-wise https://excaliburmetaldesign.com/kitchen-range-hoods/ But you'd get more of a modern, simple design. THey can also do a 'zinc lookalike', since real zinc is pricey. They can do wood w/faux finish, or do a SS w/a 'zinc' finish. this would be perfection! custom metal finish cool sconce. this comes in the gunmetal finish like that hood https://jaylighting.com/collections/wall-sconce/products/sisyphus-grand-sconce ignore this hood, but what do you think about some shelving? not the best photshop, but you get the idea. I love this hood style and color w/your cabs you could have the shelves made in the same finish Etsy has some great craftspeople https://www.etsy.com/listing/1493509274/custom-artisan-zinc-range-hoods-modern

Why do you need 4 fridges? So your prep sink is on the top wall, and cleanup sink on the island? Where will you store dishes? I have that setup and it works perfectly. My dishwasher is on one side of the sink and my drawers with all my silverware and dishes on the other side of the sink. I may also want to offset the sink so that the sink and dishwasher are not directly across from the cooktop. That's what I have with 48" aisles and it works fine because it's offset a bit. I can't read any dimensions, but I can tell you that two people cannot sit at the island as shown - the knees of the folks at the corner take up the same space. Yes and the other issue is that you need 60" between the edge of the island and your sofa. It doesn't look like you have that. 1'6" and 2'8" lower drawers, 12" slide out, 36" cooktop, 12" slide out, 2'8" drawers, 24" dishwasher, 36" sink, 18" trash, and corner cabinet to be added. Do yourself a huge favor and forget the 12" slide outs. They are not good. You're better off with wider drawers . You have 62" to the left of your cooktop. You'd be better off with a 2 three drawer cabinets. One 30" and the other 32". And your dishwasher needs to be to the right of your perimeter sink but in reality, you probably do not need a dishwasher. Your trash pullout should be where you do your prepping as it generates more than where you cleanup.

What are you willing to change? I see the uppers are still in place as well as the counters. If that has to stay you are locked into the old layout. Honestly the old layout generally is fine but I would do a lot of tweaks like building in the fridge, extending the cabinets to the ceiling, single bowl sink, etc. But all of these things are predicated on full replacement.