Hi Tim.
So first off, I would make sure the two networks can talk to each other. I assume you have this in place. However, I do recall that there is a setting in Control4 to allow it to talk to other networks, you have to list the network names otherwise it won’t do it. To rule this out, can you temporarily move the HA instance onto the same network is C4?
You mention that you are pushing all lights to Control4 from HA, but I’m not sure if this integration works this way around, in my scenario it’s used to pull all lights from Control4 into HA?
Also as far as I know this integration will not provide media control. I too would love this feature, but it’s not something I could help with from a development stand point otherwise I would.
I’m working towards removing C4 from my house and completely replacing with HA. The media control and whole house distribution is a major stumbling block for this currently.