I think this is an area where the theory book is mixing Dramatica terminology with "normal" terminology, and confusingly, at that. I also suspect that there are hints of additional layers of the theory mixed in there, too. These are layers that have only been touched upon by Melanie, Chris, and Jim, and are not part of the current theory.
A more direct answer: The way the model works currently, Story Goal is not arbitrarily assignable, and will be in the OS. However, what the readers label as the goal of your story can be arbitrarily assigned (based on what you most flesh out in the final product), but any "changes" to other such points will have to be done through your muse.
I only have the Windows version, so I'm unaware of a capability to reassign the Story Goal to another throughline. However, if such a feature exists, I would suggest ignoring it. Instead, determine where the emphasis in your story should be, and use that as the goal. Let the Story Goal remain in the OS Throughline, and encode the structure based on that. Use your Storytelling to change the focus.
Also, a little anecdote: When I first read that portion of the theory book, I tried to do exactly what you are now. I tried to figure out what the quads were for those points, if there were any, and how they would rotate or be affected by changing the Domain of the Story Goal. It turned out to be a futile effort. The model used by the software is too biased toward the Story Goal being in the OS, so it's better to leave it there and focus on Storytelling emphasis. The greater the emphasis on a throughline, the more it will feel like the goal lies there.