I seek the Trinitiarian God, defined by the CC in the 4th century, and accepted by almost all Christians regardless of denomination.
Yes, very worthy, on the face of it. But it is already a conclusion and therefore a filter. Good luck.
You said: the teaching office of the Catholic Church is not a valid, true, or especially useful standard by which to measure reality, regarding only the teachings of Jesus the Christ.
What you have said is deep but it did not answer the question: Did Jesus the Christ leave the world with a valid, true, useful standard by which to measure reality, (BTW, the context is Marian worship so I will wait for one more answer and then digress

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regarding only His teachings, so that every generation has access to them, as opposed to just the generation of His apostles?
My apologies. for some reason I was not getting the question as you spell it out in this form.
Imho, no, He left a methodology by example of discovering it for oneself, and that methodology has been occluded by the exigencies of time, politics, translation, and interpretations of those yet on the side of the coin of seeking that has not found, and who have not discovered the substance of the coin as distinct from its faces. However well intended and thought to be protected and inspired the records may be, they are extrapolations, and weakened, to put it as kindly as possible. And yet they live and are available today, but unrecognizable to those deeply invested in the Christian view, as that purports to be the Truth, and has in its Catholic version the weight of astounding and profound, but finally nearly useless, intellection behind it.
Imho, the Catholic mystics that gained the ultimate insight did so despite the intellectual structure, which served chiefly as a koan, though the idea of the Son of God and that Sacrifice is a true story, but whose personal (not in the Protestant way) implication is almost invariably missed due to the assumptions surrounding it, assumptions made by some who didn’t make a necessary leap. It is so to this day, and there is therefore a standoff between dogma and experience that in the Church, for the most part, is nearly insurmountable.
Is that more in the line of an answer? As for the Marian part of it, that is relatively but not absolutely a factor. Just that if it was taken more seriously and in a more Universal sense, it could be “…right, just, and helpful to our salvation.” That last word is also hyper misunderstood in the Christian context, again hinging on the understanding of the original Teaching.