Actually looks like Sonoff created their own plugin for HA. Those directions are terrible BTW.
If someone could decipher all that code it could be recreated in groovy, or if they had a published API it would be a heck of a lot easier. Maybe they do have it somewhere.
Found some sort of docs but a lot is in another language, some sort of Chinese.
I have no plans of doing it myself. Someone who owns the devices and has the motivation to get it working would need to tackle that project themselves.