At the very early stages of development I considered if/how planetary missions could be added to CIU. I ultimately decided that it was way too much effort, because those missions work on a completely different framework on CI5.
I did, however, think about how you would randomly generate such missions and I came up with something roughly equivalent to Planetary missions generator . The main issue was few (none?) of the existing enemy formations could be used, because they don’t take account “terrain areas”. A whole new set of waves specific to each terrain would have to be created.
So the idea was shelved. It’s quite possible that it will eventually make it in CIU, but it’s definitely not going to be during Early Access.