On the Equivalence of "Let Him be Anathema" and Matters of Faith and Morals

When in a biblical passage, such as Gal. 1:8--- > But though we, or an angel from heaven, preach a gospel to you besides that which we have preached to you, let him be anathema. or when an Ecumenical Council, such as the Council of Trent, declares, for example (on Justification): > 18. If any one saith, that the commandments of God are, even for one that is justified and constituted in grace, impossible to keep; let him be anathema. Can we (from a Catholic perspective) justly conclude that the matter in question is either a matter of faith or morals, and therefore, cannot be rescinded by the Catholic Church?