>This one is kinda buried in the list. This is what motivated the harsh austerity measures in Greece. So an entire country was punished because of a bug in a spreadsheet.
That isn't true. This paper indicated that moderately high levels of public debt constrained economic growth. As you have pointed out, the paper was riddled with errors and the evidence that moderately high levels of public debt slow economic growth isn't really there.
What happened in Greece is quite different. Lenders lost confidence in the Greek government's ability to repay their debt. Partially because there was re-statement of public debt that increased the debt level by 11% overnight.
What the Greek government did after that to get out from under this was to cut spending (austerity). Economists have always been sceptical that this would work since during a recession is the very worst time to cut spending since it reduces cumulative demand at a time when it is already down.
Indeed it did not work as we all know, but Eurozone lenders were not willing to allow a partial default which is what should have happened and being in the Euro means that there is no possibility for a devaluation.