As Jecko comments, true Catholic tradition is more than its catechism. I am unaware of a novena that fits this description, but traditions do change and it may, for example, have been a Catholic tradition with Church approval when your priest was a young man. It is hard to imagine an ordained priest inventing something like this. Also, perhaps the claims that statues of Mother Mary have shed tears of blood is evidence of an earlier tradition that Mary herself shed tears of blood.

A different example is the Catholic tradition of limbo. Thomas Aquinas hypothesised that a merciful God would not consign to hell innocent babies who died without being purged of Original Sin through baptism. Aquinas said these innocents must dwell in limbo, a place between heaven and hell, alongside virtuous but unbaptised pagans such as Plato and Moses, born before Jesus had come to explain things. Thus it became a Catholic tradition and had Church approval as such. When I was a young child, many years ago, the brothers taught me about limbo as fact.

Now, the International Theological Commission says:

It is clear that the traditional teaching on this topic has concentrated on the theory of limbo, understood as a state which includes the souls of infants who die subject to original sin and without baptism, and who, therefore, neither merit the beatific vision, nor yet are subjected to any punishment, because they are not guilty of any personal sin. This theory, elaborated by theologians beginning in the Middle Ages, never entered into the dogmatic definitions of the Magisterium, even if that same Magisterium did at times mention the theory in its ordinary teaching up until the Second Vatican Council. It remains therefore a possible theological hypothesis. However, in the Catechism of the Catholic Church (1992), the theory of limbo is not mentioned.

So, if you were taught the catechism before 1992, or enquired more fully before Vatican II, you could have been told about limbo and assured that it is real, but you would not easily find such a teaching now. Recent Catholic theological speculation tends to stress the hope, though not the certainty, that unbaptised infants may attain heaven instead of the supposed state of limbo, so we discover that limbo is not, and may never have been Catholic doctrine. Nevertheless limbo is undoubtedly a strong Catholic tradition, has been taught by the Church and had Church approval, even though it never entered into the dogmatic definitions of the Magisterium.

Since Vatican II, the Catholic Church has begun to move away from its former teachings about limbo and treat it as no more than a hypothesis, and there have been suggestions that the hypothesis will eventually be abandoned. In fact, Bishop Geofrey Robinson says in Confronting Power and Sex in the Catholic Church, page 122, the Second Vatican Council set aside many things that had been consistently taught for more than a thousand years. As with the example of limbo, this shows that what is important is what is approved and taught now, rather than what may have formed part of an earlier tradition.

We know what Tradition is by looking at the Church, and we know the true Church by looking to see if it is

1) one,

2) Holy,

3) Catholic,

4) and Apsotolic.

For more information, I would read St. Vincent of Lerin's Commonitory (400s: right after the second Eccumentical Council) and this commentary on it:

http://www.newadvent.org/fathers/3506.htm

http://www.calledtocommunion.com/2011/05/the-commonitory-of-st-vincent-of-lerins/#identity

Christi pax.

A bit of background: traditions and Tradition

Sacred Tradition

When the Church refers to Sacred Tradition, she is referring, not to practices, but to a body of doctrines that are not explicitly found in the Sacred Scriptures.

A few examples of such doctrines (some of which rise even to the level of dogma, or solemnly defined doctrines that are subject to divine and Catholic faith):

• The Immaculate Conception of the Blessed Virgin Mary. Although the Scriptures refer to Mary as kecharitomene (one who has been definitively filled with grace), it does not affirm in black and white that she was born without the effects of Original Sin.

• The doctrine of Original Sin is itself an inference not found explicitly in the Scriptures.

• The Assumption of the Blessed Virgin Mary. This event occurred, presumably, after most of the the New Testament was written, and so could not have been recorded in it (unless Revelation 12 is a veiled reference).

• The canon of Scripture. The Bible does not itself contain a “table of contents;” which books actually belong to the Bible is a doctrine transmitted by Tradition.

• The number of the Apostles. Nowhere in Scripture does it say that the office of Apostle is limited to the Twelve, or to the Twelve and St. Paul, or that the office would cease after the Apostolic Age. This is only known thanks to Tradition.

All of these are doctrines that have been taught, with differing degrees of explicitness, from the earliest moments of Church history. We can be sure that they are true, because of the infallibility that Christ endowed to his Church, and it is the task of the bishops in communion with the Bishop of Rome (the Pope) to be stewards and interpreters of these truths. In this capacity, they exercise the Church’s Magisterium, or teaching authority.

Ecclesial traditions

Sacred Tradition is to be distinguished from so-called ecclesial traditions (written with a lowercase T), which are various kinds of practices and popular beliefs that have developed over the ages.

Some of these practices are explicitly sanctioned by the Church (such as the various forms of the Sacred Liturgy), and others (such as novenas, rosaries, processions, and so on) are forms of popular piety, practices that people have found helpful for expressing their faith over the years.

Among ecclesial traditions are also certain popular beliefs that are not the subject of faith (many of which are probably historically spurious).

For example, the story of Veronica wiping the face of Christ, which is common in the Way of the Cross, has no basis either in the Scripture or in Sacred Tradition. There is nothing wrong with thinking that such a person really existed, but neither does the Church require such belief. Similarly, most depictions of the crêche show three Wise Men, but in fact the Scriptures do not specify their number.

No ecclesial tradition is completely set in stone (in contrast to Sacred Tradition), although, of course, ancient and venerable practices are generally to be respected. For example, even with the reforms of the Mass after Vatican II, the Roman Canon—now the First Eucharistic Prayer—was left essentially unchanged from the pre-Vatican-II Mass.

See the Catechism of the Catholic Church (CCC) numbers 80-90 for a full treatment of this topic.

How to judge if a practice is good and holy

There are objective ways to judge if a given practice is good and holy, or if, instead, it tends toward superstition.

• It should be in complete conformity with Church teaching (including, evidently, what is contained in Sacred Tradition).
• It should lead people to greater love and devotion to Jesus Christ.
• It should lead people to the Sacraments and to the reading of the Sacred Scriptures.
• It should foster obedience, humility, and the other virtues proper to Christian discipleship.

(These criteria are derived from the way that the Church judges Marian apparitions, which fall under the category of popular piety.)

Ultimately, it is for the Church’s Magisterium to decide whether a given practice, or even a popular belief, is helpful or not.

Regarding the specific concerns of the O.P.

It seems to me that a novena to Mary’s tears of blood is not a cause for concern. It is simply an example of popular piety.

No one is requiring Catholics either to believe that Mary shed tears of blood, or to take part in the novena. Both the popular belief and the popular practice are entirely optional. On the other hand, neither do they contradict any truth of the faith. If someone finds such a practice helpful, then he should feel free to participate. If not, then he is free not to do so.