There are three English translations of this that I have found, which all slightly differ, but they are all good defences for the absolute necessity of Baptism. I have seen some BOD advocates take "commonly" to mean "often, but not always"..but we see that is not the case if you actually read what is being taught
These are three translations
Pope Clement V, Council of Vienne, 1311-1312, ex cathedra:
“Besides, one baptism which regenerates all who are baptized in Christ must be faithfully confessed by all just as ‘one God and one faith’ [Eph. 4:5], which celebrated in water in the name of the Father and of the Son and of the Holy Spirit we believe to be commonly the perfect remedy for salvation for adults as for children.”
One Baptism, which regenerates all who are baptized in Christ must be faithfully confessed by all just as ‘one God and one faith’ (Eph 4:5). We believe that baptism, celebrated with water in the name of the Father and of the Son and of the Holy Spirit, is the perfect remedy for salvation both for adults and children in common
All are faithfully to profess that there is one baptism which regenerates all those baptized in Christ, just as there is one God and one faith’. We believe that when baptism is administered in water in the name of the Father and of the Son and of the holy Spirit, it is a perfect means of salvation for both adults and children.
The distinction between adults and children is between those above and below the age of reason. This can be seen in the very next sentence, which says:
Yet because, as regards the effect of baptism in children, we find that certain theologians have held contrary opinions, some saying that by baptism guilt is indeed remitted in infants but grace is not conferred...
Infants cannot desire the Sacrament, as they do not have the use of reason. The only "Baptism" infants can receive is the Sacrament of Baptism, administered in water.
Pope Clement V teaches that this baptism (The Sacrament, in
water) that infants receive, which is the
only Baptism that infants can receive, is
in common (shared between the two), the perfect means of Salvations for
both them and adults