There's some cool concepts here, but this was a miss for me. I like most of the puzzles here, so I'll keep going.

In particular, there were several common letters with the sator square and the printed square, which made it seem like that was the right track. I also didn't realize pater noster would play as major of a role as the square itself -- it seemed more like a side thought

I'll type it in again, but I typed it in 3 times, both minuscule and majuscule.

Thanks!

Are you sure that answer you came up with isn’t accepted by the website? Maybe try it again.

I used hint #2 and found I was on the right track. It told what order to arrange the letters in. I found that a bit disappointing, especially as simply knowing that I was doing the right thing by trying to solve the anagram could have kept me going. Also, there was another particularly good one. Demigod Lake.

I'm sticking with "deified" as my answer even though the solution box doesn't accept it. It fits all the criteria.

Interesting. There's an Orpheus Lake, but that's not the answer. Several lakes named after 7-letter greek demigods, but none of them are the answer. Time, perhaps to move on from this line of inquiry. Also, no famous person, Lake, I can find with the first name of a demigod

the anagram also spells demigodlake. searching for lake names that might fit.

Following the tack that finding the anagram and answering that riddle would be a reasonable 7-letter solution.

Devilishly clever puzzle!

I had to look up 7 letter palindromes, but I managed to get that far on my own at least

I thought for sure the solution would be to make the letters into a Sator Square and then find the common theme between those words to find the solution word. The format for this puzzle felt a bit random. I hesitated using clues because I didn't want that "oh, duh!" moment, but I'm glad I did. Not sure I would have figured this one out without them. (With that said, I am /loving/ this book, so I don't mean to sound overly critical.)

The premise of the Sator square is a red herring. The letter frequencies in M’s make a symmetrical square impossible. That’s so unsatisfying! Methinks you have the basis for a much better puzzle, but this one felt like you phone it in, M.