Leo XIII was NEVER pope
Leo XIII taught heresy while fraudulently posing as pope
Leo XIII Bestowed the Supreme Order of Christ on a Heretic
The following information, serves to clearly condemn Leo XIII. Not even the heretical Dimond brothers could argue against this.
Combined with his three heresies, namely the separation of Church and State , God is the Father of all men and that there are sacraments among unbelievers, that he made a statement that the Church is not opposed to "real and lawful liberty" right before teaching that the Church does not condemn rulers who tolerate public expressions of false worship, then the above account of Leo XIII blessing Jews and proclaiming them to be his children is not surprising at all.
Certainly Jews are not children to the pope according to the flesh, but how could they be so according to the spirit unless they were also children of God?
For more about the above heresies of Leo XIII, please read "Leo XIII was NEVER pope".