"Otmar Issing said the central bank would lose credibility if it shifted the inflation target."
"He said the job of the central bank is to actually hit the target, not shift the target once you have missed it."

Mmm this is designed to make it sound like changing the target would be akin to shifting the goals to claim you scored one.
But moving the target from 2 to 5% when you are stuck at 1% is quite the opposite. It's an increased recognition of having failed the economy.

As it is, the bank is aiming for too low, and failing to achieve even that.

Earth provides enough to satisfy every man's need, but not every man's greed. Gandhi