First, a big thank you to all of you who patiently help me with my questions. The help I got on Re-do of question about 3 level filter problem + sortan question was a real breakthrough for me this week. The resulting file, linked to below, has made my process much faster. But that is just the latest of so many ways you all have helped me.
And second, I got a bit of help from ChatGPT3 today, and I wanted to share the results with you, too, in case anyone finds it helpful.
What it is: a non-JavaScript way to show hidden text on the same line in a way that works when exporting to static html. And it works as a macro, and works inside a details element.