Christopher, I think Castle was exaggerating the contents of the diary to suit his purposes. The diary was read by Rick, and we saw how giddy he was throughout this entire episode. He's also a mystery writer. He probably embellished the style of the diary for dramatic flair. We know that Castle gets carried away with things he enjoys and as for using his imagination to match up the characters with his friends is perfectly natural to me. Anyone of us would probably do that without a visual representation already available to us.
Sometimes I think you're overly critical of this show. I rarely see you type anything positive or FUN about it in this thread. As a writer yourself it would be interesting to get your perspective on things instead of just poking holes in the plot. Oh, and I'm not saying you aren't having fun watching this show but it just appears that way. I'm all for being critical when it merits it but it just seems like you don't have fun watching this show.