Have to admit, there's a lot that's frustrating about your reply.
1: You can't subscribe to changes on GitHub in a way that helps here. Moreover, you have one repo for all runtimes. I only am interested in updates to Unity.
2: Not sure what you mean to imply by the unitypackage mirroring repo. It's listed as the preferred method for installing the runtime in Unity. Why would I go anywhere else?
3: Should I be expected to just subscribe to the entire (noisy) Unity support forum for a potential new meaningful post from you? At least make a single changelog announcement post, so we can just subscribe to that. Pin it and instruct everyone to do so.
4: Again, my desire is to not just occasionally check on pages and grep for changes. I'd like to be notified when changes are available... like the asset store handles.
5: As davidsvson said, it's difficult to even tell what version I have installed in Unity at any given time. I end up checking my own commit history, hopefully I included what date the download page said. Why don't you use version numbers, and include it in the files?
6: Lastly, I'm far from a lawyer but this is the only asset we use that seems to have that issue. What's the incompatibility? Skimming the Asset Store and Spine Runtime licenses, I don't understand what it'd be.
Overall, and this is getting into emotional territory, my impression from using Spine and implementing the runtimes for the last year is that your company isn't user-, animator-, or developer-centric at all. I'm constantly frustrated by the unhelpful responses from your company on this forum. My animator is frustrated with the lack of support for common animation-industry techniques. It feels like you begrudgingly support all these different runtimes, where none of them get the attention they deserve (jack of all trades, master of none).
We're constantly left wondering "who and what is Spine for?" when our seemingly basic desires are completely unaddressed. We've paid a lot for this software, and the support is abysmal.
We know there is still a lot we can do to improve the runtimes and we are actively working on improving them.