In Catholic debate, the Pope is the last instance. All disputes previously unresolved end in him. So, one can have confidence, inasmuch as he knows the mind of the Church as expressed by the Pope.
Again, -- I said it before -- this "everyone's a pope" rap is a caricature. It is only accurate on some metaphorical level. When someone tells me "The Holy Ghost taught me that 'by works a man is justified; and not by faith only' (James 2:24) means the opposite of what it states" all I can say is, -- Gee, who made you pope?
I Cor 12-14 is not all that obscure.
Folks who collect together for worship, study, teaching as described in I Cor 12-14 should at least soon be able to prayerfully discern what is authentic and what is not BY HOLY SPIRIT'S AGENCY.
Either He helped settle the canon in those similar meetings, or He didn't.
If He didn't, then all is up for grabs.
If He did, then we can have confidence about the canon's essentials, at least--PARTICULARLY as HE LEADS earnest Believers in to all truth about those Scriptures--bit by bit, step by step in the life of each believer, uniquely tailored to the needs and God ordained growth in each believer with their varying degrees of cooperation in being conformed to the image of DADDY'S SON.
Similarly, if a local congregation meets to assess the accuracy, Holy Spirit birthedness, of a given prophetic/Holy Spirit gifts input . . . then there ought to be SOME varying degree of confidence about that--not flawlessly--but some reasonable degree of confidence.
Why not flawlessly? It's not the Canon that's concerned.
And, of less significnace but still a real factor--There hasn't been several hundred years of such discernment and groups operating on a given input/msg/document.
Individuals as described operating in Holy Spirit and He in them I Cor 12-14 are not described therein as little popes. INDEED, THE WHOLE COUNSEL OF GOD IN SCRIPTURE would include mention of a local congregation finding a humble wise old codger to help decide matters--especially vs taking them to a secular court.
Note that Paul did not say find the Bishop. Go to the Cardinal. Call the college of Cardinals; Collect the leading "fathers" [talk about Scriptural violation there! LOL] together to decide the issue; call the magesterium . . .
Instead, call on some humble wise old--probably out of the limelight--old codger--perhaps someone with food in his beard and plenty of burps out at least one end . . . but who is humble and wise . . . let him decide the matter.
There's no hint of bureaucracy there.
There's no hint of collective hierarchical leadership speaking from on high, there.
There's no hint of professional clergy deciding major issues there.
There's no hint of professional sanctimonious theological experts directing the serfs there--it's QUITE THE OPPOSITE--THE SERF DIRECTS THE CONGREGATION FROM WISDOM AND HUMILITY.
There's no hint of layering on bleachers full of fleshly elevated pontificators with a chief flesh driven pontificator propped up with a whole edifice of tradition and vain glorious adorations and elevations driven by the flesh for the glory of the flesh vs the glory of God.
There's no hint of trumped up justification for bureaucratic CONTROL--HEAVY HANDED CONTROL--OF THE IGNORANT SERFS.
There's no hint of the ignorant serfs being unable to handle life and spirituality on their own without magehysterical-ium inputs from on high.
There's no hint of GOD ALONE PLUS A CAST OF tens of THOUSANDS to say what God REALLY meant given He's so inadequate to the job.
There's no hint there of God checking in with the multi-layered bureaucracy to be sure He doesn't get it wrong according to THEIR PONTIFICAL CONTROL FREQUENESSES.
Seems pretty clear, to me. No little popes. Just brothers and sisters following Scripture AND HOLY SPIRIT. Rather like
GOD DESIGNED IT, PLANNED IT; EXECUTED IT TO BE.