An engineer is required to sign-off on conformity here, anyone buying needs to verify that and the engineer's insurance.
Thats part of the problem here. The onus is staked in favour of the seller - rather than the buyer. Here , every potential purchaser has to embark on costly engineering surveys before purchase. IT would be much simpler if the seller had to produce a file for each and every potential buyer documenting all of the signoffs, wiring diagrams, plumbing diagrams and every modification done to a house showing full compliance. Hence this is the Finnish system and as a result housing and office standards are extremely high and from sale to sale completion can be 7 days (I know of someone who did this).
For example, on Christmas day, 3 weeks ago, whilst guest at a 1950's common dormer designed house, (new houses would be much much more expensive) I sat at a dinner table in a shirt, when the temperature outside was below -20C. It reached -38C on one of the nights. Heating was not on in the downstairs , only the upstairs...radiator TRV was set to '3' ie midscale....the house uses a regular old oil burner. Inside the house it was +23C - so there was c.60C delta thermal gradient across the walls, doors and windows. Again , this is a 1950's house, the owners are in their 80s OAPs not able to maintain property much, not one of the new swanky houses that are available now with passive certs and mechanical ventilation systems. .
I didnt once see a jumper, hot water bottles, big duvets, blankets on sofas or dressing gowns with the other guests, even in the upstairs .
So clearly we are doing something wrong with our housing standards , given our much benign weather climate.
On return to Cork, we have the heating on morning and evening , about 6-8 hours every day , when the temp is a mere +5C, and this has been the case in each and every Irish house I have lived in - and this has been quite a few all over the place.
So, for the OP, his stressful experience would not happen there - I mean it is a joke considering the sum of money been paid and he seems to be in a catch 22.