Can you change the "The crawl failed to produce a WACZ file!" error massage to "Error: The crawl failed to produce a WACZ file" and change the text color to #B00020 ? Also, is it possible to add some suggestions of where users should fix in order to avoid error message? Try manual crawl or something?
Below the error message, can you add "< Go back" button so users can go back to previous page to fix things?