Those quotes indicate discussions trying to find responsible ways to use available resources to cure unacceptable fuel leaks. The language is casual in nature due to the e-mail system; ie it is chatting via the keyboard. Whoever it was who gave you copies of the e-mails is misguided, ill-informed and guilty of a serious misdemeanour.
Regarding the single post rectification flight before deployment: how many "test" flights in the UK should satisfy the engineers? I would say one single flight was enough. Then there would have been the deployment flights (2), then the 1st ops flight. Every flight would have been given a proper post-flight check for any faults.