The words written in the notebook are likely the following:
"Something so peculiar should make off with the motor". - Bulbapedia
It is unknown who owns the chateau and the notebook, however there are ghosts that appear there. It could be assumed that they own it.
Sometimes, what seem to be the ghosts of a little girl and a butler appear in a bedroom on the first floor and in the dining hall, respectively. - Bulbapedia