Very useful topic for me, thanks. Even though it's been a long time, the information was useful to me. And especially the information on the link you sent.
@Zwer2k my expectations seem correct. I created a bug report that also includes a rudimentary workaround.
https://github.com/mysensors/MySensors/issues/1496#issue-968399284
@GLAB No worries, was in a similar situation.. My perspective was on what the Node could be made to provide, not what could be done within Domoticz to address the requirement - eg Had heard of Dummy counters but had no experience nor understood their purpose, nor had ever used scripts.
I had been sending a logical ON/OFF as well as a cumulative total from the Node and hit the same hair-pulling scenario as yourself.
Now only the ON/OFF is sent and the short script makes the transposition within Domoticz to a dummy meter (I think kWhr) using the internal clock in Domoticz.
Have fun