"Same issue with Comment cela se fait-il que ... ? which is simply redundant, as it literally means How come this that ...?"
I mean. All of these expressions are redundant (if translated directly into English)! E.g. "Comment cela se fait-il?" would be "How does that, it, make itself?"
So, while it's good to know that "Comment cela se fait-il que" would strike French speakers as redundant, as a guide to English learners "avoid redundancy" is just taunting.
