Would imagine there would have been a Tech Rep or equivalent overseeing the maintenance input. But how many and what was their responsibilities?
Some airlines send reasonably large teams, technical, materials and commercial people to these inputs, others just send the bare minimum (even just one) so potentially they have to be a jack of all trades.
From personal experience doing checks on your own is a mammoth undertaking and whilst I set boundaries with the MRO to witness close up inspections, be out when functional tests are being performed and witness final engine runs etc, you cannot be everywhere 24/7 during however long the input is. Not trying to justify anything but if there was only one Tech Rep onsite then there is absolutely no chance they can keep a full eye out on the maintenance being performed when having to deal with everything else.