@franzstein
I agree with your wish to ‘only’ adopt the weather-adjustment plugin to the new API structure, but also struggeling with coding skills. BTW: the new API is based on JSON data returns, the old one (or the plugin) uses XML structures which drives things for me not easier trying to ‘rewrite’ the code.
Nevertheless: I tried your ESP8266 solution but struggled to compile the code. An error occurs within the “RTC_DATA_ATTR int raindelayCount = 0;” data definitions. I tried to include the RTC libraries in Arduino IDE but without success. My platform would be an ESP8266 NodeMCU 1.0 (ESP-12E) module. Do U use a special ESP module here which has other RTC capabilities or definitions?