A lot of the in-game books can be translated, but most of them have the placeholder/filler text about April Fool’s Day. Mattison’s diary however has both Hylian Script and Gerudo Letters, which isn’t surpising with parents like these, and a unique message not found in any other in-game books.
For explanation: Patricia is Riju’s personal Sand Seal, and that beast even has its own Hyrule Compendium entry. It is likely that her mom taught her much about Gerudo Town and its inhabitants to prepare Mattison for her journey there.
Just. Precious.