There remain two problems you don't address, Joe.
Firstly, the grassy plot is about 10 years square, 100 sq yds, which if divided into orderly burial plots allows for about 50 burials. Divide 796 by 50 and you get an overcrowding factor of 16. Each child has about 1 sq ft. That corresponds with the description of what must be little better than a charnel house now. Even London's plague pit was less crowded.
The second is how the kids got there. There is quite sufficient evidence to support a claim of institutionalised child abuse amounting to genocide of a minority, children born out of wedlock. It is consistent with the immorality of the Magdalen Laundries, moreover, and witnesses survive. The only question remaining, really is the extent across Ireland it was practiced in, and we alreay know three more convents are holding their hands up. How many more are still trying to brazen it out?
Go reread Matt 18 on those who deny the Kingdom of God to children. You differentiate between those directly and those indirectly responsible, their superiors: I don't think that's valid, as this convent was so close to the Cathedral, it must have been the closest Religious house of any, in plain sight across the racetrack. That takes the problem pretty high.
By comparison, the Belgian situation, although lesser, certainly reached to and saw the active participation of the Cardinal Nuncio, so I'm in no way minded to excuse these bosses either. And that means that however sainted the pew-fodder (pay, pray, obey...) the heirarchy itself is perverse to the core. I've seen them, holier-than-thou, hypocrites. At least I own those whose deaths in the domain I worked in may be vaguely attributable to me.

And that once more brings me back to something I commented on earlier. In Matt 5-8/9, Jesus expounds on his vision of the Church - it's one without heirarchy. Without buildings. Without half the paraphernalia imported from the ancient Greeks in the 10th-15th century by Aquinas above all else. Do you need these priests, or is your vocation strong enough to relate to God directly?