Hah, that one is tricky. There were three errors regarding child element population, but the agent would likely only be able to recognize and act on the second one to fix the issue.

As another courtesy for your patience (and because this site is very cool), I have a fork of the project here with the fixes applied that you can import into Shakespeare if so desired:

https://gitlab.com/chad.curtis/pop-card-fork.git

Hope that helps!