In this case, the carbon and oxygen are coming from a much more mundane source: the solar wind.
When high-energy particles from the solar wind collide with molecules in Venus’ upper atmosphere, they carry enough energy to break some of those molecules into their constituent atoms. Since the Venusian atmosphere is almost entirely CO2, you should expect this process to generate C and O ions — which is exactly what we’ve now observed!
Maybe an uncommon opinion, but as someone who’s invested hundreds of hours into both games, I actually prefer the 2d experience of ROR quite a lot more than the 3d of ROR2.