You cannot have a proper discussion of the Eucharist without understanding its true validation and authenticity. The USCCB is not the total teaching Magisterium of the Church and thereby subject to error. The USCCB does not speak for the entire teaching Magisterium of the Church and, if this is what they seemingly have agreed to, then they are wrong. Just because a person ‘thinks’ he or she has the Real Presence outside of the Catholic Church (if that were possible), does not make it so. Rule of thumb: if the conclusions any organization comes to is in keeping with the teachings of the whole Church, then the conclusions are valid. If not, they are wrong.
The notion of relativism has no place in the Eucharistic Presence (“I believe it to be so; therefore, it is”). How absurd. Suppose someone believes that the moon is made out of green cheese. Therefore, that makes it so. Again, absurdity. Only the Catholic Church has been blessed with the gift of the Real Presence of Christ in the Eucharist - His body, blood, soul, and Divinity (including the Orthodox. Why? Because they have a valid priesthood with valid sacraments - when protestants rejected the ministerial priesthood, they rejected the Real Presence, though they may have retained an understanding of it in some way.).