Father in heaven, it is right that we should give you thanks and glory: you are the one God, living and true. . . .
I can see a bit of ambiguity there. The Trinity is composed of three persons, The Father, the Son and the Holy Spirit. Together they comprise God.
Hmmm. It would seem we need to stop here.
According to Catholic teaching, because each person is God whole and entire, the Preface to EP IV here is, doctrinally, perfectly fine. The reason is because all the persons are wholly and entirely in each of the persons: i.e., the Father is in the Son and in the Holy Spirit, the Son is in the Father and in the Holy Spirit, and the Holy Spirit is in the Father and in the Son.
True each is God in his own right but it takes all three to comprise God.
To say “each is God in his own right” is quite correct. To say “it takes all three to comprise God” is actually a bit ambiguous.
“But each [person] is God whole and entire” and each of them “is that supreme reality, viz., the divine substance, essence or nature” (CCC 253). Consequently we can confidently say, e.g., that “the Father is God whole and entire; he is that supeme reality, the divine substance, essence or nature” and, of course, we can say the same for each of the other two persons in the Trinity.
I think what you might have forgotten a bit here is that each person of the Trinity is wholly in the others also. Thus, as the Catechism says, “the Son is wholly in the Father … the Holy Spirit is wholly in the Father…” (CCC 255). The Son and the Holy Spirit, therefore, are each of them wholly “in the Father.” No one, in other words, is “missing” in the Father.
To someone not well schooled in theology or the dogma of the Trinity hearing this could misunderstand and think that the Father alone is God and that the Son and the Holy Spirit don’t really matter.
Alright, to make a long story short (and I will give the long story) one cannot say that the texts (whether pre-reform or the reformed) necessarily implies that “the Father alone is God” - not, that is, without doing violence to the text.
------- THE LONG STORY -----
(Pre-reform Text
Father in heaven, it is right that we should give you thanks and glory: you are the one God, living and true.
Which, as we have seen, is perfectly correct.
(Reformed Text
It is truly right to give you thanks, truly just to give you glory,
Father… for you are the one God living and true . . .
See:
old.usccb.org/romanmissal/samples-priest-prayer4.shtml
I think it would be wrong to say that “the Father is alone” (i.e., that he is* alone -**“period!*”, in the sense of being
solitary ) ; for God is not solitary and, therefore, it would be wrong to say that God (either the Father or the Son or the Holy Spirit) is solitary, or that the Trinity is solitary, for that would seem to ascribe an imperfection to God.
Consider that it can be said (even our Lord affirmed it) “Hear, O Israel,
the Lord thy God is one God, and
him only shalt thou serve.” Consequently, we can also say that the Father (or the Lord Jesus or the Holy Spirit) “is one God.” And this is what is affirmed in the Preface to EP IV.[/INDENT]
I grant, however, that saying “the Father alone is God” does not sit well at all on pious and Christian ears, because “alone” almost inevitably seems to apply the idea of being solitary; however, and to the point, saying that “Father… you are the one God, living and true” (and both versions say this same thing) is, in fact, perfectly orthodox. If it were otherwise, then saying “the Lord thy God is one God” would necessarily mean that God is solitary, which of course it does not mean.
-------- END OF THE LONG STORY -----
Just playing devils advocate here
And you played the devil’s advocate well

This is pretty tough stuff but it is also very enlightening.
In conclusion, what is said in the Preface to EP IV is perfectly orthodox, for the Church believes that the Father is truly “the one God” who is “living and true”; for the Father is one God, and we do not believe in three gods, but one God: Father, Son and Holy Spirit, each of whom is wholly and entirely God. Moreover, one cannot conclude any heterodoxy from the Preface without doing violence to the words or, otherwise, questioning the Catholic dogma of the Trinity. Finally, the Eucharist is being offered
to the Father specifically, in keeping with the Lord’s command to do this in remembrance of him, and in immitation of our Lord’s own praise, thanksgiving and sacrifice, which he gave and offered to the Father on behalf of humanity, with which (sacrifice) we unite ourselves to in the holy sacrifice of the Mass.