Steps to Reproduce:
On Commons main page, click on the picture of the day.
Enter a caption and click "Publish".
Nothing happens, caption is not saved and no error is shown.
You probably shouldn't be offered a caption "edit" button on protected images.
This might be unusually tricky because it has cascading protection from the main page.
On beta, the code doesn't remove the edit option completely but does show warning messages when the user attempts to Publish.
For captions (the missing template shouldn't be a problem on prod):
For statements (again, templates should be on prod, need to double check things display properly there though):
Current Commons practice does not inform the user that featured images are protected until an edit attempt is made. It's probably okay to continue with that model, but we would need prod to work like Beta.
 User sees an appropriate and accurate error message when clicking publish on a structured data panel
 The error messages includes community-managed templates, displayed properly.