Hey Tim,
I really like your implementation! The WebView is quite generic and sandboxed by design, since we have to support many use-cases and don’t control what is rendered (or executed) in it, so you are bound to reach its limits when developing more complex functionality. Persisting state is very difficult, as you are experiencing, either due to the security restrictions or the fact that it reloads each change.
Thanks for sharing your screenshots. They really make a strong case for us to add a TableView, so you don’t have to code this all on your own. I’ll pass this on to the product team to consider 
Tom