Hi, I haven't made one yet, since It's just been me I've been focused on content. After a few more updates, probably after 1.0.0 I will take a break and post a guide.
If a scene is incomplete it won't show in the gallery. That might mean that there are alternative routes that contribute to the same gallery. It's an older issue that I will try to avoid in the future.
A lot of those scenes stem from Yellow text, so I recommend saving and going back to explore when it suits you.