Re: Thinking way too hard about this, but...
Well, the mirrors ARE the work of Desaad, the Apokoliptian God of Torture, y'know. It's not surprising that he could gimmick them so that they cause Supes some trouble. As for 'an intellect that rivals Lex Luthor's', that varies from story to story. In the Silver Age, particularly in the Weisinger era, that was indeed the case, but back then he had super-EVERYTHING. He was super-strong, super-smart, super-fast, had super-vision, super-hearing, super-smell, super-digestion, super-ventriloquism, and who knows what else. You name it, he was super at it. This was not the case during his early Golden Age adventures, though, and as this looks like a Bronze Age-era comic, I'm not sure whether it was the case then, either. I think that generally, Superman is portrayed as intelligent and quick-thinking, with a fair understanding of science, but he's not a genius.