Can I safely assume the calligraphy signed by OSensei on page 9 of that text are the ones he would have translated as "The Art of Peace"?
The page 9 of the text that you refer to contain a calligraphy for the kanji characters for the term "aikido." Although others such as Mr Stevens may certainly interpret
that term as such, I personally would never translate
"aikido" as "the art of peace."