Happy are they that hear. their detractions and can put them to mending.
It means whoever wrote it is horrible at English. Aka it makes no sense.
A sentence that should have O(n) complexity is being written as O(2^n*n^n).
In bad English it means that someone is happy that X realized they had a problem or a shortcoming and is working to address the problem
Are you reading the bible?
It's from Much Ado About Nothing. (Shakespeare circa 1598). It means that if you can recognize your faults and fix them you will be better off.
Lay off the bud