@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.
@NeverDie I can give my thoughts here, and we can move it later to another thread if necessary.
The bigger selling points, at least for me:
Every project is a self contained directory, even the boards configuration, bootloaders, libraries, code and build procedure
I have a project template for mysensors (mainly a platform.ini) that I copy for each node that I create.
I can manage everything with my known tools (vim, make, git, etc)
I like to play with arduino and electronics, but have other interests (Family, friends and 3 small kids...) so I usually have little time to spent in my hobbies. Platformio allows me to just have all the configuration in code and know 6 months ahead that I can do a "make clean && make upload" for a particular node without issues, even if I lost my PC, as everything is in my gitlab account.
Also the FW of my 3dprinter must be complied and uploaded with platformio (marlin 2.0) so I can have only one tool for both hobbies.