Impossible to trace at this point? You think it will mysteriously appear in an archive somewhere?
As in whatever archives might have existed prior to both world wars are now most likely gone and its impossible.
Regional identification was strong then, Sok. What if he had called himself a Silesian? ;) ;)
He was born in Kraków and because he was a med-level patrictian he had to speak fluent Polish to do business (he would have dealt with commoners who didnt speak Latin and river trade was completely dominated by Poles).
So no he wouldnt call himself a Silesian.
Even now, some are pushing for regional autonomy.
They had it before the war, they never denied being Polish though.