Eric G. Miller asks by what right hymns sung at Mass are amended to incorporate inclusive language (April AD2000). The answer is by no right at all.
In 1995 The Sacred Congregation for the Doctrine of Faith issued the document: Norms for the Translation of Biblical Texts for Use in the Liturgy.
As the instruction applies not merely to discipline but to revelation, it cannot be changed by bishops or local bishops' conferences. The document instructs, inter alia, that the Church must seek to accurately translate the inherited texts. It contains the instruction that there shall be no systematic substitution of the masculine pronoun or possessive adjective to refer to God in correspondence to the original text.
Some may claim that hymns are not biblical texts and are not, therefore, covered by the above instructions. I would argue, however, that their contents are inspired by Divine Scripture and their mutilation is in defiance of the spirit of the law.
North Blackburn, Vic