Awesome
Given GitHub's announcement to sunset Atom I've stopped developing this extension and have instead ported it to VS Code, here.
sane-indentation package
This package monkey-patches the indentation logic in atom in an attempt to come up with something more, uhm, sane. This is now using the output from the new tree-sitter parser to decide on the right indentation.
This package is transitional. Once we merge this into atom core and the language packages this package will go away.
See sample.js for an example.
Note, this package currently only works for JavaScript (incl. JSX), HTML, Python, and C/C++.