At Leaning Technologies, we are working on preserving _all_ flash content by running the original x86 Flash plugin via WebAssembly virtualization (CheerpX). If you want to read more:
Amazing work! Years ago Mozilla was working on a javascript implementation to help support legacy flash content on a Flashless web, but that got quickly abandoned before it mature significantly. Glad that someone else is working on it with a more modern approach.
You are referring to Shumway. I was working at the time on Lightspark, another FOSS implementation. All these efforts, including the recent ones, like Ruffle, are doomed due to the sheer complexity of implementing Flash from scratch.
Our approach is different. We run the binary plugin safely in the browser via WebAssembly virtualization.
https://medium.com/leaningtech/running-flash-in-webassembly-...
https://medium.com/leaningtech/preserving-flash-content-with...
A presentation about the architecture of the system: https://www.youtube.com/watch?v=7JUs4c99-mo
Feel free to drop me any question: https://twitter.com/alexpignotti