And what tells if they are right or not? Neither Masters (necessarily), nor people (still less necessarily), but reality, even if Masters or people, or both, conspire to smother it.
And how, exactly, does reality "tell" whether anyone is right?
Is it ever possible that somehow someone might find reality to have been wrong?
Has reality ever testified in a courtroom? Can reality be sworn in at the witness stand?
Which language does reality speak? Is it verbal?
When reality tells something, does it make a sound?
Does reality require a person to interpret it? If so, how does the interpreter of reality not become the entity that holds all the power?
(There are a LOT more questions.)
Before determining how to perceive reality, one must first determining that it really exists. The currently prevalent subjectivist philosophy does not acknowledge the existence of reality in the objective sense. Your questions boil down to asking what reality is.
The worldly man compiles his belief system by subconsciously absorbing subjective opinions on reality from his milieu. He usually forgets the origin these opinions to pridefully imagine they came from within himself. In reality, he acquires the default worldview of his surrounding community. A few individuals may think for themselves, but even these are highly influenced by their surroundings. The only sure means of consciously choosing a belief is to choose membership in a community where that belief prevails.
Those who imagine they independently develop opinions are thereby blinded to the real origins of their own thinking. Modern propaganda takes advantage this blindness by sending subtle signals expertly designed to trigger what the targeted subject falsely imagines to be spontaneous ideas originating from within himself.
Modern Catholics accept false teaching in the form of subjective opinion from apparent authority because they have lost connection with the principle of objective reality.
I am sure that your questions were provocatively written only to start conversation, but they could be taken as petulant whining in another context. "How can you expect me to believe in reality if you don't tell me how it communicates?" might be one interpretation of those questions.
Reality simply is. It speaks through vectors like mother's intuition, empirical observation, Revelation, long-established folkways, and the traditional teachings of the Catholic Church. Any subjective opinion in conflict with such things is most likely divergent from reality. Man can only perceive reality through the filter of subjectivity, but avoiding delusion requires persistent pruning one's opinion by drawing clear-eyed conclusions upon ongoing circuмstance.
It was once understood by everybody that all opinions of any source differing from observable fact or infallible truth were certainly wrong and that, as a corollary, opinions ambiguous enough to be possibly interpreted as differing from reality were suspect. Modern rejection of this principle betrays disbelief in the existence of reality.