Absolutely stumped on what to do with a certain late game solution

Hey everyone, I've been remiss in asking for outside help at all while playing, but I think I've hit a complete brick wall here. I've recently completed filling in all the spaces on the castle grid thing in the precipice, and received the message "CIX add six tor lor ett", or, translated out of gobbledygook, 109, add six counterclockwise (word east)/(eastword). I've been racking my brain and I truly have no idea what to do with this solution. I was really hoping it would be self-evident once I had completed the grid. I have noted that many of the places I found letters for it, the letters spelled out something related to where I found it. The Grotto had "I"s and "O"s, the kennel had a cat playing with the letters cat, and so on. I've gathered from some blue tents memos that there is something else I can do with the chess room beyond solving it the normal way, probably involving a castling move, but my only idea there didn't work either. I carefully built my house in a way to have a king and a rook on opposite sides so I could castle the pieces on the chessboard, but it didn't do anything.

If anyone can offer a gentle nudge in the right direction here, even just where I should be looking for the next hint I need, I'd really appreciate it!