We can do some more research here, but last time we looked at this the sandboxed networking configuration of Chromebooks prevented Roon from being able to communicate with the Core on the local network.
Obviously, it would be great if something had changed with regards to networking on Chromebooks, but that’s not something we can change, nor does it have anything to do with our Chromecast support.
We’ll take a look and see if anything has changed here, but unfortunately I haven’t heard anything to that effect.