After chatting with Legal (@Slaporte) today, we need to make another update:
We need a better error code when a user tries to use a different license than CC0. We will need to add into the documentation on how and where to update the wording for this error message.
It's important that this wording comes from the community, and in this instance, any Admin on Commons can update the error message, we just need to tell them where it's at in order to let the community take charge.