Paraphrase this "large debt loads can lead to painful spells of deleveraging and economic depression as has occurred in Japan for most of the last twenty years" total debt matters, private debt has decreased, but public has almost compensated. 

So net debt has reduced only slightly, so growth remains anaemic.

The bill for the fiscal stimulus will eventually need to be paid with implications for real activity. In the simulations, the stimulus expenditures are financed with increased public borrowing until 2012. Beyond 2012, a fiscal consolidation occurs to return public debt relative to GDP back to its initial level. During the consolidation period, where taxes and/or spending adjust, the level of GDP will be lower than it otherwise would be if no fiscal consolidation was required..