What are you actually trying to say?
He was only in Canada for eight years and he didn’t become a US citizen until 2005. What’s your point? Do you disagree with the timeline?
I’m saying that on receiving Canadian citizenship that Cruz Senior probably dropped Cuban citizenship. The 1947 law required it with some exceptions, as you’ve noted. (I couldn’t get your last link to work), and when Cruz Sr adopted US citizenship, he dropped only Canadian citizenship, suggesting again that the Cuban had already been dropped.
So, odds are Cruz Jr has only US citizenship and Canadian citizenship, if he hasn’t already dropped it. I know he was to the paperwork to that effect. Although, with his father dropping it, I can see why he would think it didn’t apply to him.