Cheeriop,
As far as I know there has been no official release of the API, and frankly I don't expect one for general use (solely my opinion). There are perhaps some agreements that have been made to foster product growth with individuals with proven technology and already established uses. I am OK with that. These units are sold primarily "as is" to for people to use as a weather station.
There are other open avenues established , such as the custom server option, that , in reality, offers "near" the same benefits. As a developer , you should be able to understand how to use for your own benefit. The fact that there is a way to do this is extraordinary, sure, there is not documentation on it, and probably for good reason , such as the manufacturer would then have to support the documentation . Hence, you can peruse this forum and see how other's have done it.
I read back, I'm sorry, but I didn't see you requesting specific help from anyone, and as you can probably gather, this forum is not operated or moderated by the manufacturer (although they may comment) of the products in question and advice given is purely voluntary. You seem to be getting upset that no one has offered you help for a question you have not really asked.