I dont see heaps of logic in that. I am not saying its wrong. Just dont see how it could happen. Any boosted engine is gonna have blowby under boost.
The ring lands were said to be broken, do they look burned?
Nissan has always been known to overfuel their boosted engines.

The closest logic to that I can think of that, is anything like that is what I have been told from an oldbloke that tunes/messes with alcohol engines.
Guys that run alcohol easily suffer engine problems from bad tuning. The reason being is alcohol is so cold. If they run an engine and it detonates. The next lot of alcohol to enter that cylinder is going to cool the hot metal to quick and cause problems.
Fuel is nowhere near as cold as alcohol, but enough of it will still cool without igniting.

The only way I can see to prevent unburnt fuel from passing the rings, is to ignite it as its entering the cylinder, And that just isnt going to work.

Only real way to know the cause of the problem, is to run/tune the next engine with a good gas analyzer.