For people going to see the movie without any knowledge of the EU... he's a coughing robot. Movies should stand on their own and provide the audience with all of the information they need to understand things going on. You can't just throw us a coughing robot and expect us to go, "Oh! He's totally some general who was maimed in battle badly and provided with a robot body... with extra limbs... and robotic agility and he must... have... a cold? Lung cancer? Because they could replace his severely damaged body with robotics but couldn't give him properly functioning lungs or robotic ones?"
Yeah, even accepting that he's "not a robot" the idea of him being a coughing android, cyborg, or whatever is stupid.
I have almost no knowledge of the EU and I could tell from the movie that he was a cyborg, even before I saw the second Clone Wars TV series. kind of hard to not to notice it after Obi-Wan opens his chest and fires a blaster into it killing him.
Regardless, he coughs! He fucking coughs! They could seriously provide him him with a cybernetic body but not cybernetic lungs?!
As I said I thought Mace did that to him when they abducted Palpatine at the end of the second Clone Wars TV series. I don't tink he coughed in the scenes after the opening of the movie.