Why would Paul write in inspired scripture to hold fast to oral tradition if it could not be accurately kept over time?
It makes sense to me that we are to take seriously the informal or verbal guidance of others, in humility. After many centuries, however, culture, traditions, etc., can accumulate. One isn't necessarily taking seriously the informal or verbal guidance of Paul or other Apostles, so much as one is holding onto what became normative in the community one is involved with.
From time to time going back to the Scripture itself to see the light it sheds on traditions, sounds like a good way to simplify or re-focus or to discard or avoid certain things as needed.
Certainly what people CLAIM is tradition isn't as binding on the conscience as what is actually the written witness of Apostolic teaching: the Bible.
How do you know that you're understanding Scripture correctly? How do you know that when you look at the "whole counsel of Scripture", that you're putting the pieces together properly?
One indicator of a possible problem is when it comes to my attention that other Christians, particularly other Christians throughout many centuries in many times and places, disagree significantly.
It's important for Christians to stay connected with other Christians and to be aware of what other Christians have thought and done throughout the centuries, everywhere, so that if I have a hobby horse or particular principle that I'm over-emphasizing, for example, I would become aware of other Christians, perhaps many many other Christians, who put a different emphasis on things, reminding me of other Scriptures or principles from Scripture which I've neglected.
Tradition includes but is not limited to oral teaching of the Apostles. But Tradition also includes the Church's understanding and transmission of divine truths, including what texts belong in Scripture which took a number of centuries to discern even though the Apostles left no such explicit table of contents in writing or orally that we know of.
In the second century it was well known that four authentic gospels existed, that various apostolic letters were authentic, and that these were in use in churches, and it was known that various apocryphal and gnostic texts were not Scripture.
That it took some time for community leaders to gather together and discuss materials that some were less familiar or confident with, just means that after some years passed there were some questions on some cases. This does not mean that we need to accept every technical or practical interest of a particular set of Bishops as universal essential truths just because they call them traditional, especially when such decisions were made after a major Schism or when various abuses gave reason for serious concern.
By looking at how traditions and theoretical explanations or pronouncements look in the light of Scripture, things can be sorted out better, re-framed, and what was misguided or mindlessly accrued over time may be handled appropriately.
All that being said, the answer to your question is that the Holy Spirit objectively reveals truth to the Church. The final trust is in the Spirit and Christ's promise to send the Spirit to the Church in that capacity.
And what is inspired Scripture? Inspired Scripture is what God has revealed. It has objective content. It has been circulating for centuries all over the world and used by Christians.
People can and do err, whether they are Protestant, Catholic, Orthodox, Fundamentalist, or Pentecostal. Yes the Holy Spirit guides the church, but this is not an argument for a Christian to simply trust without question all the details on specifics among various traditionalists that don't seem essential and/or don't seem to measure up to what God has clearly revealed.
The inner witness of the Holy Spirit gives glory to Jesus Christ and guides the individual in truth, and after a Christian prayerfully considers the full counsel of Scripture and humbly desires to be teachable by other Christians, keeping one's eyes and ears receptive to what other Christians have said and thought for centuries so one may be taught by the Body of Christ collectively also, one may very well feel convicted that a particular detail or tradition is non-essential, distracting, misguided, or plain old wrong.