I agree that having the conclusion come soon after the climax is a bit anti-climactic. That is one thing that I don't enjoy much about Atelier Sakura games; they always begin the ending sequence right after the climactic scene. The story's climax should have some time to settle in before the ending sequence, and it doesn't necessarily have to be much time, just some time to digest the situation and see the world after the peak of emotions. But knowing that he still has to add Hana's POV and has extra content planned on top of that, I wouldn't judge him for making the ending a bit brief.
For the scenes, the escalation should already top off at the climax, so there wouldn't be actions that escalate beyond that. There are other things you could think about for a scene than just the acts directly, such as the location, the situation, the decisions, etc. In the beach scene, for example, the tension here isn't only about the "condomless sex" but also the fact that they're out in the open, and a stranger is watching them, which let's them handle the situation in a fun way. He is very good at making scenes, so I don't doubt he would think of something fun.