Ouch indeed... truly sorry to hear that.
Any fueling map balances power output against reliability... and emissions, and economy, and drivability, and...
But-- Engine components all have physical mechanical limits - how much force and heat they can transmit, and how many loading cycles they'll undergo before failure. There are low loads that can be cycled almost forever, and high loads that will cause an instant failure. In between are the levels that cause fatigue and incremental damage, and these are the load levels that lead to predictable premature failures. You approach them at your peril.
Unfortunately, your piston has become a data point of when a piston failure will occur with a GDE tune.
-dave