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"all those graced by God with a true faith in Jesus Christ as Lord and Savior" defines the visible Catholic Church. There are Christian communities of faith that have some parts of Catholicism right, but they themselves deny being Catholic, nor are they wanted in with the heresies they profess alongside the "true faith in Jesus Christ". The Eastern Orthodox is a more complex case, which I can explain in some length if you are interested.

SECOND QUESTION
What is the meaning of the affirmation that the Church of Christ subsists in the Catholic Church?
RESPONSE
Christ “established here on earth” only one Church and instituted it as a “visible and spiritual community”[5], that from its beginning and throughout the centuries has always existed and will always exist, and in which alone are found all the elements that Christ himself instituted.[6] “This one Church of Christ, which we confess in the Creed as one, holy, catholic and apostolic […]. This Church, constituted and organised in this world as a society, subsists in the Catholic Church, governed by the successor of Peter and the Bishops in communion with him”.[7]
In number 8 of the Dogmatic Constitution Lumen gentium ‘subsistence’ means this perduring, historical continuity and the permanence of all the elements instituted by Christ in the Catholic Church[8], in which the Church of Christ is concretely found on this earth.
It is possible, according to Catholic doctrine, to affirm correctly that the Church of Christ is present and operative in the churches and ecclesial Communities not yet fully in communion with the Catholic Church, on account of the elements of sanctification and truth that are present in them.[9] Nevertheless, the word “subsists” can only be attributed to the Catholic Church alone precisely because it refers to the mark of unity that we profess in the symbols of the faith (I believe... in the “one” Church); and this “one” Church subsists in the Catholic Church.[10]
[...]
FIFTH QUESTION
Why do the texts of the Council and those of the Magisterium since the Council not use the title of “Church” with regard to those Christian Communities born out of the Reformation of the sixteenth century?
RESPONSE
According to Catholic doctrine, these Communities do not enjoy apostolic succession in the sacrament of Orders, and are, therefore, deprived of a constitutive element of the Church. These ecclesial Communities which, specifically because of the absence of the sacramental priesthood, have not preserved the genuine and integral substance of the Eucharistic Mystery[19] cannot, according to Catholic doctrine, be called “Churches” in the proper sense[20].
RESPONSES TO SOME QUESTIONS REGARDING CERTAIN ASPECTS OF THE DOCTRINE ON THE CHURCH (footnotes at source)

This Church, constituted and organised in this world as a society, subsists in the Catholic Church, governed by the successor of Peter and the Bishops in communion with him".[7]

Peter was not the head of the apostles. That title belongs to Christ alone.

"Ye call me Master and Lord: and ye say well; for so I am." -- John 13:13

The bishops are not the "successors" to the apostles. The apostles had no successors and Peter had no successor because in order to succeed the apostles a man needed to be a witness to Christ's resurrection.

"Wherefore of these men which have companied with us all the time that the Lord Jesus went in and out among us,
Beginning from the baptism of John, unto that same day that he was taken up from us, must one be ordained to be a witness with us of his resurrection." -- Acts 1:21-22

The Magisterium is not the authoritative teacher of the church. That title belongs to the Holy Spirit alone.

"But the Comforter, which is the Holy Ghost, whom the Father will send in my name, he shall teach you all things, and bring all things to your remembrance, whatsoever I have said unto you." -- John 14:26

"Howbeit when he, the Spirit of truth, is come, he will guide you into all truth: for he shall not speak of himself; but whatsoever he shall hear, that shall he speak: and he will shew you things to come.
He shall glorify me: for he shall receive of mine, and shall shew it unto you." -- John 16:13-14

"But the anointing which ye have received of him abideth in you, and ye need not that any man teach you: but as the same anointing teacheth you of all things, and is truth, and is no lie, and even as it hath taught you, ye shall abide in him." -- 1 John 2:27

And the primary means of this instruction is the word of God made known to us by the gift of the indwelling Holy Spirit.

I realize this unsettles many members of the RCC who feel adrift at having to search the Scriptures for themselves, and thus they prefer to rely on what they are told by an authoritarian body of fallible, inconsistent men. But that is not God's plan or purpose in giving us His word.

According to Catholic doctrine, [Christian Communities born out of the Reformation of the sixteenth century] do not enjoy apostolic succession in the sacrament of Orders, and are, therefore, deprived of a constitutive element of the Church. These ecclesial Communities which, specifically because of the absence of the sacramental priesthood, have not preserved the genuine and integral substance of the Eucharistic Mystery[19] cannot, according to Catholic doctrine, be called "Churches" in the proper sense[20].

According to Scripture, there is no such thing as "apostolic succession." Those who have been given true faith in Jesus Christ are the church of Christ, guided by teachers and pastors, none of whom are "successors to the apostles."

According to Scripture, there is no such thing as "sacrament of orders." There are only two sacraments in the New Testament, Baptism and the Lord's Supper.

According to Scripture, there is no "sacramental priesthood;" there is the priesthood of all believers who make up Christ's church on earth.

The "eucharistic mystery," or transubstantiation is a pagan abomination of the true spiritual sustenance Christ instituted at the Last Supper of our Lord.

The church of Jesus Christ on earth is made up of all the elect of God, from all the nations and races and eras, chosen by Him from before the foundation of the world to be among His family.

"For whosoever shall call upon the name of the Lord shall be saved." -- Romans 10:13

"According as he hath chosen us in him before the foundation of the world, that we should be holy and without blame before him in love:
Having predestinated us unto the adoption of children by Jesus Christ to himself, according to the good pleasure of his will,
To the praise of the glory of his grace, wherein he hath made us accepted in the beloved." -- Ephesians 1:4-6

As for being "proper," there are some churches more pure than others. As the Westminster Confession of Faith states (including footnoted Scriptural proofs)...

"V. The purest Churches under heaven are subject both to mixture and error;[10] and some have so degenerated, as to become no Churches of Christ, but synagogues of Satan.[11] Nevertheless, there shall be always a Church on earth to worship God according to His will.[12]