Bafa funding - heating deviates from the application

What are your experiences regarding the sample checks by Bafa after one year? One out of 1000+ applications being checked, then I wouldn't worry. Or I have to try to get the plumber to handle it. But he has no clue about it.. We are currently in conflict with him because he forgot a part without plaster behind the shower. Right on time for moving in, the wall had to be opened again. So we have been without the main bathroom for 3 weeks.

Hello. Our heating system deviates from the application. The reason for this is that according to the installer, although the old heating system is still subsidized, there are increasing problems with it.

We previously had the Aerotop Slit 07 M-RX and now have the Aerotop Split 07 M-R. The only difference I see is that the x version runs on 240 volts and the new one on 400 volts. Are there any other differences, see attachments. What are the advantages and disadvantages of 240/400 volts?

My actual question, however, is how I should proceed with regard to Bafa. The funding approval from Bafa is available. Both heating systems are on the subsidy list. The plumber has no idea and doesn't care/react.

A hydraulic balancing was recently done, but I don't have it yet.
What is meant by an electricity meter? Attached is a picture of our box. I have purchased a heat meter and the plumber installed it. He now wants to install a second one. But can't the consumption be calculated by offsetting between the electricity meter and the heat meter? The upper meter should be for consumption calculation, right? A photovoltaic system is also present (just for your information).

Who carries out the adjustment of the heat pump to the building? Is there proof for this?