A downdraft system is a chore to clean. Purchase a new unvented stove hood instead.

Downdrafts aren't ideal. That's particularly true when using gas. They're better than nothing. But you'll hate your decision of going with a downdraft, if you ¹regularly cook ²fragrant foods in an ³open floor plan kitchen on a ⁴gas stove. The more of these points you checked off the less happy you'll be.

Of course, reality always gets into the way. Not everybody can have a properly sized externally vented overhead vent hood.

Relocating the range or finding a creative way to route the ducts is ideal. But if that cannot happen, then switching to an induction stove can reduce the need for a high powered venting solution. And at that point, it might also make sense to look at Vent-A-Hood's ARS recirculation system. From reports on GardenWeb, it's the only recirculating hood that does work. It's not a 100% replacement for an externally vented hood. But people do seem to like it.

buy another stove hood it would be more appropriete

You need to relocate the stove. Downdrafts are horrible at venting, installing another one won't change that.

You should get a proper range hood and connect it to the ducts, but if you want to keep it in the island I can attest that it will work out just fine. I LOVE having my range in my island! I'm so happy not to cook facing a wall!

A commercial range needs commercial venting and that will never happen with a downdraft. I use vent-a- hood for my venting with a commercial range I have actually never seen the recirculating ones but worth checking out . IMO the best place for a range is an outside wall with proper venting and the last place is an island , maybe there if you have a one storey house and the venting can go through the roof.