Does Justification leverage a separate Storyform?

Can Justification use a distinct Storyform that leads to the actual story, or must the Justification directly tie itself to the main Storyform?

I think so, but it isn’t necessary. Justification is the process to mask the Problem element. So I’ll advise that you leave it without a storyform. Just let your imagination go wild. But if you still need some handholding of sorts, you can color the problem element of your MC with the Issue. Since it’s thematic, it’ll sit well in terms of relevance.