I wish I had your confidence DFC.
You are right about the eng change/c of a mistakes happening previously. However this is specifically what Part M is designed to avoid so there is little improvement although huge amounts of money have been expended.
The cost of maintaining technical libraries can be huge. Single type or single manufacturer would be far more sensible. Costs would be reduced to a minimum.
The worst case scenario would be a maintenance organisation with its own Part G looking after multiple types and trying to recover it's costs.
I seem to remeber that the technical documentation for the Arriel engine alone ran to several thousand pound. So unless the owner can provide the books this cost has to recovered.
I feel that eventually this system will settle down, however I believe I already see them moving the goal posts yet again.!!!!!!!!!!!!!!!!!!