Really great writeup. So people stop asking the obvious question, here is the GitHub issue that clearly shows Ruffle doesn’t support ActionScript 3:
https://github.com/ruffle-rs/ruffle/issues/1368
I recently picked up a copy of Flash MX to use on an old PowerBook, highly recommend others do the same. As many have commented, today’s authoring tools are poor substitutes (someone should do a list of the superior abandonware versions of SaaS products).