This add-on is a big hack and I would not recommend using it.
Home Assistant does not have an API to provide entities in Home Assistant. We don’t have this because we don’t want vendors to implement a proprietary Home Assistant API.
Our goal is an open home without vendor lock-in, we don’t want to be part of this problem. We want vendors to create an open API that can be added to Home Assistant and other home automation projects alike.
Some internals of Home Assistant are accessible via the API and are being misused by this add-on. It will not be a good experience.