Impractically Terraforming Venus

I think this plan is impractical, but the coolest possible way I could terraform Venus. As I mentioned before, Carl Sagan had a plan to have a city encased in a plexiglass bubble, filled with Earthlike air. Placed in Venus's atmosphere, this floats like a balloon, about six miles over Venus's inhospitable surface, where the temperature and pressure are Earthlike.
We deploy millions of these in a Dyson-like swarm. (Dyson's sphere, as described by Dr. Dyson, is not a solid object, but a swarm of satellites in clever orbits that never quite collide, and prove dense enough to capture 99% of a star's output.) The swarm orbits around Venus, and when they're close enough to each other, we connect them with steel rods, and then form "bowls" with metal plates in the area between the rods and the bubble cities. Venus now has a second "surface". Below, the supercritical carbon dioxide cools in the darkness, while above, a large planet with lots of room. We fill one bowl with imported soil, and grow plants in it. Preferably crop-plants. Any waste shucked off by the farming is put into the other bowls to compost. When the composting is done, they are super-fertile farming areas. The process accelerates until the entire surface is full of greenery. At that point, the plexiglass can be removed from the bubble cities, as human beings could now breathe this planet's air.
Down below, the carbon dioxide cools in the darkness until it is a liquid. It probably won't reach solid temperatures at this pressure. I can imagine the farmers above siphoning small amounts off on occasion. As this gets used up, the rocks below can become a second resource. Or, thirdly, the gap can be used for waste disposal, because no human being's ever going down there.
Now at the beginning, I said this was impractical. Even one sagan-bubble city would be a massively expensive trillion dollar undertaking, with some very difficult engineering in the process. This is talking about making millions, possibly even billions, of them. And as for the connecting stage, I'm not sure earth even has that much steel.