I agree his composure is a bit low. Look at his goal in the 2 all draw against Barcelona when Benzema played him in, he stayed calm and composed, you can literally see him pick his spot, and he coolly blasts it past Victor Valdes on his near post. Again against Barcelona, in the Super Cup when Madrid won 2-1, he flicks it over Pique, and his next touch is a bad one, and he shows great composure to spin round, regain control of the ball, take another touch to set it up, pick his spot, and put it past Valdes.
You can also just look at his penalty stats to show he has good composure. Penalties are as intense as it gets in a football match, and Ronaldo's records show he isn't one to lose his head, he stays calm, and more often than not, scores.
The last thing I'll say is, you're never going to agree with everything SI says, you're not going to agree with everything in the game. If something bothers you, that is what the editor is for. Some people may consider it cheating, but in my opinion, if you're only changing some attributes by small amounts, ie giving Ronaldo 12 or 13 composure, then there is nothing wrong with that. If you're giving Andre Santos 173 CA on the other hand...