Thank You @Steve Babiak, @David Krulac, @Greg Wilkins for the answers, all very useful! Sorry for the late reply, my BP account had some glitches the last 2 days.
I looked further into this and it appears that the plaintiff's lawyer did mail both the county's Register of Wills and the Bureau of Individual Tax Inheritance Tax Division in Harrisburg informing them of the foreclosure before the sheriff sale, so after the defendant passed away (already a year before at that point). I see 2 options:
A., Do you know if in this case these 2 institutions should respond back with their tax liens that would then be attached to the distribution of the sale proceeds or else these liens would be wiped out? My understanding is that this is the case with the Free and Clear Tax sales - as long as other lien-holders are properly notified, the lien is wiped out. Wondering how it works in the case or mortgage foreclosures.
B., Or is it that finding out if there is inheritance tax due is the plaintiff's due diligence - they might end up as the high bidders on the auction after all (obviously not because of worrying about the quality of the title a 3rd party bidder would get). If this is the case, would it make any sense to contact the plaintiff (bank) or their lawyer to rectify it afterwards (e.g. by paying off the taxes due from the sheriff sale distributions)? Now this is obviously a long shot but some of you might have such experience or know certain paragraph from, say a foreclosure act.
Obviously, if neither of the above 2 is the case then I am stuck with paying off the balance, which apart from the money aspect, poses some challenges: not knowing the deceased's DOB or SSN, neither the exact mortgage balance at the time of death to be able to determine the tax base (an amortization schedule won't help here because there are already penalties, legal fees, etc. involved)
Thanks in advance for any insight!