I've been assigned to start working on a smart energy meter project, it's been like 10 years since i put any work in AC . I would be sincerely grateful for any constructive advice. Now the 3-phase meters i'm been assigned to work on are class 1 smart meters and apparently they need to comply with IEC62053-21 power consumption limits for voltage circuits which are as follows

Also the since the metrology part/ front end which consists of ,
Current Measurement: Current transformer ( isolated from mains , no neutral reference need to be connected ).
Voltage measurements ( need to be non-isolated and the neutral needs to be connected to the ground of the system ) ofcourse any modem or communication device is to isolated.
The Main SOC (MCU+Metrology) is power hog and it apparently draws around 50 mA alone , the rest of the circuit probably another 20 mA maximum. I've been hinted to study the possibility of using dropper capacitor power supplies+ DC-DC regulators which have high input tolerance (60V) instead of transformer based AC-DC ones. I've been gathering all i can to fully understand the circuit to get 12VDC , seems i'm still going no where.
For now my questions are the following,
Which type of powersupply type (non-isolated) should i use while designing the power supply ( capacitor dropper,...etc) 10VA or 2W , based on my previous calculations 10VA @ 230V will give about 43 mA which is tiny ? I'm confused help ?
How do i calculate the power efficiency of the dropper capacitor , i'm aware of the Pout/Pin but since this has capacitor the equation is not applicable ?
All my findings and work are available here :
https://www103.zippyshare.com/v/U7kgRZK8/file.html