"The previous windscreen had also been fitted using incorrect bolts, which were replaced by the shift maintenance manager on a like-for-like basis without reference to maintenance documentation"
It avoids having to avoid banging the window on sensitive equipment in the cockpit when installing or removing the window. After this incident, they don't design windows like that any more.
To ensure pressurization, often compounds are used to help seal the aircraft. PRC is one that I've used previously for this. Perhaps something similar had been used to seal the cockpit (thus helping hold the bolts in place), but there hadn't been time to re-apply (as it takes ~24 hours to completely set).
Blind copy pasting in realworld.