My machine empire can colonize and terraform. You might need to validate your files.
So you can do extreme planets? I can Terra-form and colonize planets that require atmosphere cleansing but not extreme planets, even though I can research aquatic and frozen, not barren, it's not there. Even after I research, say aquatic, I still can't colonize it, because I don't have access to the tech, I can't trade for it either. I did validate, I either get one file, that needs to be reaquired or two 4 or 5 files that need to be reaquired. I have grm mod, grm terraformer mod, some tweeks to a couple other xml files, will remove them and see if that fixes them.