Venus is quite a bit warmer than the Earth, but then it’s much closer to the Sun, and its atmosphere contains about 200,000 times as much CO2, as Earth’s atmosphere.
I doubt what the atmosphere contains has anything to do with how hot it is on Venus. Since water vapor is the major greenhouse gas, we know this by experimentation results, the water has been blown off into solar system. That’s essentially what ESA measured, Hydrogen, Oxygen, and Helium being blown away. The sun’s radiation at Venus’ distance would be brutal. I would bet they had to heavily shield the spacecraft to even be able to operate around Venus.
But with our sum total of knowledge about Venus very small, there is a lot we don’t know.
One thing we do know, no magnetosphere is very bad if you plan on living on the planet.