Hey everyone, I’m really sorry I’ve been MIA lately. I started a new job recently and its been consuming a lot of my time.
Here’s an update on this project. Everything still works for me, but I do agree, due to the complexity of setting this up it’s really not ideal.
However, there is some good news! 
If you are using lovelace, you’ll probably be interested in Karl’s @kalkih Mini Media Player. He recently added Sonos grouping support and it’s MUCH easier to setup vs. my poor hacking attempt above, not to mention offers a lot more in customization over the current built in media player component.
And if you’re not on lovelace, this just might be a reason to look into it now. I would love to help everyone get this working but I also don’t want to give false hopes since my free time lately has been next to nothing. 
But if anyone wants to get my solution working, I may have a little bit of time this weekend, so shoot my a PM and I will try to help the best I can!! Thanks everyone!