Well, it's complicated. I'm not trying to criticize this work, which is really cool, but it doesn't really tackle the hard part of types in an Erlang-style concurrent system.

To learn about the challenges of typing complex concurrent systems and some of the cool approaches for doing it, I highly recommend this talk by Zeeshan Lakhani: https://www.youtube.com/watch?v=-8jLRThHuFQ