The first subsection of Chapter II, dealing with “Active and Conscious Participation” (RS 36-42) wraps up with this paragraph:.
[42.] It must be acknowledged that the Church has not come together by human volition; rather, she has been called together by God in the Holy Spirit, and she responds through faith to his free calling (thus the word ekklesia is related to klesis, or “calling”). [Cf. Varietates Legitimae 22] Nor is the Eucharistic Sacrifice to be considered a “concelebration”, in the univocal sense, of the Priest along with the people who are present. [Cf. Mediator Dei] On the contrary, the Eucharist celebrated by the Priests “is a gift which radically transcends the power of the community. . . . The community that gathers for the celebration of the Eucharist absolutely requires an ordained Priest, who presides over it so that it may truly be a eucharistic convocation. On the other hand, the community is by itself incapable of providing an ordained minister”. [Ecclesia de Eucharistia 29; cf. Fourth Lateran Ecumenical Council, 11-30 November 1215, Chapter I: DS 802; Ecumenical Council of Trent, Session XXIII, 15 July 1563, Doctrine and Canons on Sacred Order, Chapter 4: DS 1767-1770; Mediator Dei] There is pressing need of a concerted will to avoid all ambiguity in this matter and to remedy the difficulties of recent years. Accordingly, terms such as “celebrating community” or “celebrating assembly” (in other languages “asamblea celebrante”, “assemblée célébrante”, assemblea celebrante”) and similar terms should not be used injudiciously.
In my experience, new terminology is mainly geared to developing lay engagement more deeply in the Mass, moving from a model of passive spectators to full and active participants. I’m aware of institutional skittishness about the proper role of the priest, but I have to say that this has never been as ambiguous as in communities that are not provided resident clergy. As long as chanceries retain priests for staffing at the impoverishment of smaller and remote parishes, there will remain the tension with lay leaders serving in liturgical ministry, and doing it well. It’s a challenge, to be sure. But it’s going to require accurate diagnosis in faith communities, and a pastoral and open approach by bishops. Likely less a universal prescription from Rome in search of an actual illness.