This entire nonsensical thread, that annoyed many a good Polish patriots, stems not only from ostensible lack of common human decency regarding one of the worst and most bestial atrocities in planet Earth's history but mainly from the total lack of understanding of Eastern politics.
In the East there is no Pawian-like approach of "somebody has to be wiser", somebody has to "let go". If you let go, then in the eyes of Kiev you show weakness. Poland has shown weakness towards Ukraine for the last 30 years because we thought they are like us.
They aren't.
If, as the OP proposes, instead of being assertive towards the neo-banderist attitude and elements present in the current Ukrainian politics, we apologized to them first for Bolesław Chrobry, medieval siege engines and whatnot, we would show the ultimate sign of weakness and - for the lack of good English word -
frajerstwo. Pawian-like kindhearted fools would expect that Kiev would fall into our arms after that, apologise for Volyn and allow the exhumation of victims. Everyone is entitled to be a fool, we live in a free country, but such people should keep away from foreign politics.
This is why we should work together to correct this distressing aberration.
It is hardly possible in the current circumstances, isn't it? We should, however, be more flexible in our foreign policies, diplomacy and approach towards possible future peace agreement and the conditions thereof. Much more flexible.