I'm a few versions behind on my last complete playthrough, but by the end of the first act, Rowan planned the massacre of an enemy army largely on his own, and engineered a major city falling under the control of his underling. Though... The twins both get more competent as the direct result of his assistance as well, and don't hesitate to lord it over him when his success was less than perfect.
So he's demonstrated concrete success that can be directly attributed to him, and has built a degree of authority independent of the twins, but he's still under their thumb. Whether he's content with that or not can vary depend on his choices, though that hasn't been elaborated on much at this point.