Once new animations are unlocked, they are repeatable, and the same will apply to future ones. Some past scenes aren't repeatable at the moment, but I’m considering adding a gallery for special or one-time animations as well.
Yes, I get what you mean, some of those scenes (like the Launch one) were designed as one-time events in the story, but I totally understand the wish to replay them. Right now, it can technically be revisited using save/load around that moment, but I agree that's not ideal. I'm working on a way to make more of these scenes repeatable in future updates, either through gameplay options or possibly a gallery/replay system.
That said, more scenes with Launch are coming in the next update, and the same goes for Zangya too. Thanks for the suggestion!