Thank you for the nice comment! :)
The walkthrough is only a broad strokes guide on how to get the good endings for each route, so it doesn't cover every single CG, as some of them are not necessarily unlocked on the way to a good ending :P
CGs 4 and 7 on the Misc tab are from the ballroom event, you just have to pick a different option at the start (on whether you or Toxic will go retrieve Messalina)
CG 1 on page 2 of Olli's tab, to unlock it you have to be on the path of Olli's route and set up Evandro with his childhood love (or be on the way for the Good Evandro ending by the time the prison scene arrives)
The Deniz one is just a torso-only version of the third in the set, not sure why it's not appearing in the gallery because I can see it just fine :/