Looking at the README it's not clear how indexes are managed.
Like when we create a branch and add some data to an existing table and move back to a previous branch and try to add data with the same index keys ?
If you create an index on a branch it will only be visible to the child branches starting from the point where the index was created. I encourage you to clone and test it. It is easy to compile, and it's fun! I will make a video in the next weeks.