Superior was actually a subsidiary of a Irving Oelbaum's Acme Paper company so I suspect they printed on what ever they had lying around. Acme had the money to invest in various publishing forays, including an early Canadian TV Guide-type magazine called The TV Reporter that only lasted abput ten issues.
Publisher Willie Zimmerman doesn't remember trying especially to save money by using cheaper newsprint. He says it was the same as all the other newsprint as far as he knew. His son , who was in printing suggested the printing process could have affected the quality.
Superior kept American trends in mind not so much because they sold to the States but because Ruth Roche and Jerry Iger produced all their interiors out of Iger's New York shop. So those two would be very much in touch with the new rules.
I believe Superior wasn't pursued as heavily in the States simply because they weren't an American Company. It was harder to get at Zimmerman and his partners. They did end up facing separate but similar public outcry in Canada but there was also some balance to it, with support on both sides. Although, the support for the comics tended to be more on the "What's the big deal?" side Superior had a fairly large line for it's brief span. Zimmerman and Iger made decisions over what to feature and whaty books to produce together. Romance, War, and Horror were the biggest sellers at the time so that's what Superior focused on. In the end, it was low sales that caused them to close up shop, not government restrictions. The profit simply wasn't high enough.