Thank you very much for this detailed explanation. That really helped a lot.
I have one suggestion for a plugin addition thats probably not to difficult to implement.
As an Admin, I am aware of key engineers that my team interacts on GitHub and in the forum. So we do know both identities. Do you think it would be possible for us to associate a discourse user manually with a github account via the plugin settings? This way you would enable this plugin even when it can not find the user automatically.