We have a more feature-complete reference implementation of Umbral called pyUmbral you may want to look into[0].

We (NuCypher) are using this to build a blockchain privacy layer in the form of a decentralized key management system similar to AWS KMS or Google Cloud KMS.

You can read our paper that describes our use-case here: https://www.nucypher.com/whitepapers/english.pdf

0. https://github.com/nucypher/pyUmbral