Yes, it works now!
This also means, that WU (IBM) in fact are still running the system, as in the past. All the stories that the whole system was discontinued... clearly not the case.
Thanks
The new API is already stable for years.
My dashboard-template is used by dozens of users who only upload to WU and then reload their data from WU into the website.
Weather-programs WeatherDisplay, Weewx a.o. support direct or indirect access to the data from the WU-uploading station.
There are multiple brands of (inexpensive) weather-stations which
can only upload to WU, without any other access to the data.
The new wu-API also gives you access to a 5 day forecast to use on your website.
The old .CSV access to load your data is dead. To much bots and illegal massive downloads of station-data.
A ".csv to new-AP"-bridge is implemented in most scripts which used that old .csv format.
But do check if uploading to other sites such as WeatherCloud, Awekas, pwsweather+Aeris, can be an advantage for you.
Wim
P.S. probably I will get some negative remarks, but IMHO it is still a good deal to upload to WU.