We should be careful not to overestimate the possible outcome from heating system inspections. If you read the current EPBD directive it looks like the recommendations expected from a heating system inspection are the same as from an energy certificate. I don't think you can get the same results. Heating system inspection can reasonably trigger further investigation if there is an evidence of big problems. Example: high actual consumption. Then, who cares for the building? There is heating system, ventilation system, air conditioning inspection but no "building inspection...".
I would suggest that regular maintenance of systems should be compulsory instead, including a simple check of actual consumption versus design o certified values. If there is a significantly higher actual consumption, reasons should be investigated.
This could be very simple: just join certificates database with energy distributors database.
By the way, this would be very effective, independent, cheap and straight to the objective (less actual consumption) way to check certificates....