Bestiary is an encyclopaedia that contains information about characters and enemies in the game. This just means that the update now allows you to look at previous events, character portraits and CG scenes for Dorlly and Bell, and can be viewed in the bestiary tab.
The tab for the game bestiary is located in the game menu when you click right twice from the top bar.
There have been no new pictures/events that have been added that haven't occurred since ver 0.033, which contained the event scene for Bell. You'll most likely get a new event/CG scene when the next major update, ver 0.034 happens