I agree with you on forks; if I can avoid them, I always do. I would rather contribute to an existing plugin and improve that over releasing a fork.
I reached out more than 6 months ago regarding a major bug in this plugin related to users always receiving all replies even if they selected replies only and I submitted several fixes via a GitHub Pull Request to the GitHub account duechiacchiere (which no longer exists) where this plugin had been hosted. I was ignored.
I've had many people request my fixed version of this plugin. I pointed them to my modified copy of Subscribe to Comments Reloaded in GitHub, but then when I fixed subsequent bugs, they had no easy way of updating. So, I finally decided to republish this plugin as WP Comment Subscriptions.
You can see from the changelog here the large number of things I've fixed since v2.0.6 of this plugin:
If one of you wants to add me as a contributor to Subscribe to Comments Reloaded and collaborate with me on the development of Subscribe to Comments Reloaded via GitHub, I will gladly refocus my effort here on this plugin. If you need to discuss in private, you can also email me at raam at raamdev d-o-t com.