I would say we are missing a conclusive statement and one opinion that matters.
Your quote from Saint Pope John Paul II is sound on his part. Jesus statement is not conclusive. And yes he was himself a fan of von Balthazar. Interestingly, it is von Balthazar on Holy Saturday that offers Judas unique possibility. The idea of Christ’s light in Hell. A lasting light.
SPJPII had interesting ideas on the subject. His earlier writings are not as guarded as the latter which is understandable as Pope. He maintained the Doctrinal possibility of Hell. And he offered candor of his difficulty conceiving of it never the less.
I don’t agree with your " modernist" origin of this idea.
We continue to pray for all souls in our liturgy. We have an All Souls Day. And these things would be error if we were certain a soul was damned.
These ideas of a wider, not narrower salvation are biblical and were( Also) in fact believed by Church fathers. I would say there is a robust disagreement. HE WILL BE ALL IN ALL passages are joined with the countering narrow limited salvation others ascribe to.
Church fathers and Doctors who viewed wider salvation ideas included Theophilus of Antioch, St Clement of Alexandria and ( Origen his pupil),
Theodore of Mopsuestia, Saint Gregory of Nyssa, Saint Jerome( before the Origen Issues), Esubious, Didymus the Blind , Saint Isaac , and arguably others like Ambrose of Milan and my favorite, Maximus the Confessor.
In later times, Julian of Norwich( All will be well, All will be well, and all manner of things will be well)
You actually could say Saint Augustine’s influence put his finger on the scale in advancing the wider vision of damnation.
2 Pet 3:9…The heart of God is such that desires that none shall perish.
Or Saint Irenaeus of Lyons( AGAINST HERASIES, book III,23.6)…Questioning interminable or irremediable evil( Adam).
There is really no argument to be made about modernism. Only modern forms of reinvigorated theology. In candor we don’t know. We are permitted to vigorously hope.
I would recommend David Bentley Hart’s new book, but it is modern and you seem to have a bias.