I just had a quick look at their github, and almost everything is just merging PRs from standard Godot. Either they will stay close enough to the standard code they can keep merging (in which case, why exist?), or they will eventually start getting more different, in which case they are going to need a lot more developers to do anything useful.
Look at this post about their latest "beta release", they are just linking to the godot PRs they merged: https://www.reddit.com/r/RedotGameEngineMain/comments/1gisaz...