Q: Quick question re Confirmation: Is there any canonical or liturgical prohibition on candidates taking a Confirmation name of the opposite sex?
A: There is no official legislation anywhere on confirmation names. Nothing at all in the Rite of Confirmation, the Rite of Christian Initiation of Adults, the Code of Canon Law, or the Catechism of the Catholic Church. The clear implication is that the priest or bishop is supposed to use the candidate’s baptismal name, not a confirmation name.
But the practice is widely different. I never promote the taking of a confirmation name, but I tolerate it because of the customs associated with it.
There is no prohibition against taking a name of the opposite sex. Think of all the French and Spanish male first names that include “Mary”, from Jean-Baptiste-Marie Vianney to Jean-Marie Le Pen.