Much progress, and one sticking point, with backup system
Rewrote my backup page so that it now shows a useful and more readable table of all the files that exist, along with buttons to generate or re-generate hard copies of any documents. Documents that exist are shows as date/times of their last modification. The generation pipelines no redirect, on success, to the backups page they were called from, with a hash component to make sure the page doesn't jump around too badly when there's a lot of content on it. What's there so far works great.
However, I've spent all day struggling with the problem of creating directories in which to store the individual XHTML files. They should each have their own directory so that copies of the JS and CSS can also be stored there; that's required in order to make them actually functional and portable. However, I can't get the flowscript to create a new directory. After many trials, I've finally posted a message to the Cocoon mailing list. We'll see if anyone can suggest what might be causing the problem.