I have the results of my Transformation on my Openhab thats good. But If I want the same Item value sent to Grafana via InfluxDB (outside from Openhab) it gives me the raw value of the item! which means JSONPATH($.ANALOG.A0) and not the results of “Voltage [JS(VoltageCorr.js):%.1f]”
Well, you started off by needing to extract the part you were interested in from the MQTT payload using JSONPATH.
When you do not use JSONPATH, you do not get the part you are interested in.
You cannot use two separate transformations because you have chosen to use MQTT binding version 1, which allows only one transformation.
But you can script your one transformation to do both tasks, JSON and maths.