Great 
What is the current state
It’s been abandoned for the last ~1.5 years. At this point, I suspect it could be easier to restart from scratch and possibly make the API closer in spirit to PyUAVCAN.
what are the gotchas, what is currently missing in the implementation
It is rather early-stage, I would say. It’s been envisioned to implement the support for different transport protocols which would probably require revamping a lot of the existing code unless it is redesigned from scratch. I mentioned PyUAVCAN as a sensible reference because it was designed specifically to support different transports.
who else currently has a stake in the matter
Nobody. To the best of my knowledge, this implementation is neither actively used nor developed by anyone.
You are welcome to join our dev call if you want to discuss this in real-time.