Hugh wrote:

A few years ago I and a German novelist independently tried to use the
application Flying Logic to address the same need, by flow-charting
fiction. I failed. Flying Logic is designed for other purposes; I could
bend it, but not far enough for me. I don't know whether the other
experimenter made any progress with it. (If it was a solution, it too
was potentially rather an expensive one, if I remember correctly.)

The German novelist was Andreas Eschbach, a pretty successful author on the German market. I remember him writing about Flying Logic on the Scrivener forum a few years ago but haven't seen him mention FL recently either on his website or somewhere else. It's been a long time that he posted on the Scrivener forum, he uses Papyrus Autor now (he inspired a lot of the language tools in Papyrus).