Useful side by side! But those options you are changing are based on the base color, so with a different base color to start with all of those results would be different, right?
So reset to default and change the base color of the sky first and then adjust the other settings. OR, leave it and do it in post, which is certainly easier, but perhaps not in line with your desire to master terragen.
Or perhaps even the easiest thing is to copy sky settings from one of the files in file sharing that you like, an alter that. I would just say that starting as close to your intended destination is preferable. Building up from zero can be maddening and counter productive creatively, and really is not necessary. But I do understand the desire to do everything your self as well as understand every tiny aspect. But you have already done a good unique image, so I don't think there is anything wrong whatsoever with using a setting from image sharing.
But like I said its a great image, only the color of the sky gave me any pause. And these are just some thought on the image. No disrespect meant.