They'd probably be delighted to hear that you're reading the book (and it wouldn't hurt to mention that you think it's good!)
You could mention that, and ask about the causality problem, why it seems backwards compared to the earlier description, and how you've not researched it yourself and would appreciate clarification. You can also mention that you've noticed some minor typos and ask whether they'd appreciate them for a future printing. I think it's safe to say authors would rather have mistakes not continue to be reprinted.
Second this. A few years back I wrote a chapter for a book and then the editor screwed up. With one of the other authors, we took on editing and fixing things around.
As I had seen so many versions of it, my chapter was the one on which I could do the less editing around -- I was absolutely tired of it. Lo a behold, the book gets published, I get a physical copy on my hands, and I start seeing typos and small mistakes around. Nothing too serious, but things that I would've fixed.
I know those mistakes are there. Only a handful of people have pointed them out. Those people have not only read the book, the followed it and questioned it. It's nice to be reached out, even if I already know what's wrong.
You could mention that, and ask about the causality problem, why it seems backwards compared to the earlier description, and how you've not researched it yourself and would appreciate clarification. You can also mention that you've noticed some minor typos and ask whether they'd appreciate them for a future printing. I think it's safe to say authors would rather have mistakes not continue to be reprinted.