I have added a Python reference implementation of BIP32 path templates,
that is also compatible with micropython:

https://github.com/dgpv/bip32_template_python_implementation

The FSM formal spec has received a small corrections since the
announcement, and the reference implementations (C and this new python
implementation) are tested even more thoroughly now.

I submitted a PR to the bips repo:
https://github.com/bitcoin/bips/pull/1025, any comments welcome.