Yeah so the way I plan to bring this to tauri-bindgen is through something completely different: streams.
This is essentially the same as in GRPC if you're familiar with that, if not here's the gist:

interface log {
   func start_logging() -> stream<string>
}

which would translate to something like this for the host

trait Log {
   type StartLoggingStream = Pin<Box<dyn Stream<Item = String> + Send  + 'static>>;

   fn start_logging(&self) -> Result<Self:: StartLoggingStream>
}

Similar to how the tonic crate handles this.

On the guest side this would map to AsyncIterator for JS and SomeSpecificStreamType<String> for Rust probably.

So no events in the classical tauri sense (imo superior though bc it forces cleaner code) but I hope it can fulfill all the use cases.

Edit: If you want a similar behavior to events right now under this stream model you'd use an tokio::sync::mpsc channel like so:

struct LogData {
   rx: mpsc::Receiver<String>
}

impl Log for LogData {
   type StartLoggingStream = Pin<Box<tokio_stream::wrappers::ReceiverStream<String>>>;

   fn start_logging(&self) -> Result<Self:: StartLoggingStream> {
      let rx = todo!(); // haven't figured out how to do this yet

      let stream = tokio_stream::wrappers::ReceiverStream::new(rx);

      Ok(Box::pin(stream))
   }
}

And now you can use the mpsc::Sender handles across the codebase like you'd call win.emit() (but with more safety)