Isn’t that a Protestant hymn, thus would be heretical or hetrodox in a RC church?
It is not forbidden to be sung in a Catholic Church just by virtue of it's being of Protestant origin. It does seem odd that a Protestant hymn would be sung in a Catholic Cathedral on such a momentous occasion given the abundant patrimony of Catholic hymnody, but maybe there is some notion of ecumenism behind the selection. There is nothing strictly heretical about the lyrics from a Catholic standpoint.