However you want to look at it the Council of Trent's teachings were consistent with the those of the historic church.
The church teaches that nothing we do merits grace, or eternal life, or anything-we don't even exist apart from God and He certainly doesn't need us- and yet that God nonetheless has created man such that what we do, how we respond to His grace, counts. So, for example:
"To those who by persistence in doing good seek glory, honor and immortality, he will give eternal life." Rom 2:7
"When you were slaves to sin, you were free from the control of righteousness. What benefit did you reap at that time from the things you are now ashamed of? Those things result in death! But now that you have been set free from sin and have become slaves of God, the benefit you reap leads to holiness, and the result is eternal life. For the wages of sin is death, but the gift of God is eternal life in Christ Jesus our Lord." Rom 6:20-23
"Therefore, brothers and sisters, we have an obligation—but it is not to the flesh, to live according to it. For if you live according to the flesh, you will die; but if by the Spirit you put to death the misdeeds of the body, you will live." Rom 8:12-13
More from the catechism, on "merit" in this case:
"You are glorified in the assembly of your Holy Ones, for in crowning their merits you are crowning your own gifts." Augustine
2007 With regard to God, there is no strict right to any merit on the part of man. Between God and us there is an immeasurable inequality, for we have received everything from him, our Creator.
2008 The merit of man before God in the Christian life arises from the fact that God has freely chosen to associate man with the work of his grace. The fatherly action of God is first on his own initiative, and then follows man's free acting through his collaboration, so that the merit of good works is to be attributed in the first place to the grace of God, then to the faithful. Man's merit, moreover, itself is due to God, for his good actions proceed in Christ, from the predispositions and assistance given by the Holy Spirit.
2009 Filial adoption, in making us partakers by grace in the divine nature, can bestow true merit on us as a result of God's gratuitous justice. This is our right by grace, the full right of love, making us "co-heirs" with Christ and worthy of obtaining "the promised inheritance of eternal life."60 The merits of our good works are gifts of the divine goodness.61 "Grace has gone before us; now we are given what is due. . . . Our merits are God's gifts."62
2010 Since the initiative belongs to God in the order of grace, no one can merit the initial grace of forgiveness and justification, at the beginning of conversion. Moved by the Holy Spirit and by charity, we can then merit for ourselves and for others the graces needed for our sanctification, for the increase of grace and charity, and for the attainment of eternal life. Even temporal goods like health and friendship can be merited in accordance with God's wisdom. These graces and goods are the object of Christian prayer. Prayer attends to the grace we need for meritorious actions.
2011 The charity of Christ is the source in us of all our merits before God. Grace, by uniting us to Christ in active love, ensures the supernatural quality of our acts and consequently their merit before God and before men. The saints have always had a lively awareness that their merits were pure grace.
"After earth's exile, I hope to go and enjoy you in the fatherland, but I do not want to lay up merits for heaven. I want to work for your love alone. . . . In the evening of this life, I shall appear before you with empty hands, for I do not ask you, Lord, to count my works. All our justice is blemished in your eyes. I wish, then, to be clothed in your own justice and to receive from your love the eternal possession of yourself."63
Man's main job is to get on board with God, and remain on board, following Him and His will daily to the best extent we can, and getting back on board if we slip off. He'll always work to keep us there but still will simply not force that issue at the end of the day.
As Scripture affirms in different places, we're saved, being, saved, and will be saved. Either way we work our our salvation, we make our calling and election sure. It ain't over till God gives His judgment. The idea that we're saved all at once, with no concern about compromising and losing our justified state, is a wholly novel notion.