Another way of saying this is the Matthew 17 uses the singular word “Church”. Local congregation is by definition plural. This make no sense. The author would have said “go tell a church”, “tell one of the churches”. “If he refuses to listen even to one of the churches, treat him…” . No. God is Truth and Truth can not hold different answers depending on the local congregational beliefs (think abortion, contraception etc).
Are you saying that if you see a Christian sinning and he doesn’t listen to you then you should bring him in front of the Pope at the Vatican? If I say I’m going to church on Sunday, it’s understood that I’m referring to the local congregation. At the time it was written, there was probably only one church in the area so they probably brought the matter before the pastor or the elders in the church that both of them attended.
I have some Bible commentaries. Here’s what they say:
“If this fail,
bring him before the Church or congregation to which both belong. (Jamieson, Faussett & Brown)”
“Tell it unto the Church— Lay the whole matter before the
congregation of Christian believers, in that place of which he is a member, or before the minister and elders, as the representatives of the Church or assembly. (Adam Clarke’s Commentaries)”
"Lay the whole matter open before those who watch over yours and his soul. (John Wesley - Notes of the Bible)
“If a professed Christian is wronged by, he ought not to complain of it to others, as is often done merely upon report, but to go to the offender privately, state the matter kindly, and show him his conduct. This would generally have all the desired effect with a true Christian, and the parties would be reconciled. The principles of these rules may be practiced every where, and under all circumstances, though they are too much neglected by all. But how few try the method which Christ has expressly enjoined to all his disciples! In all our proceedings we should seek direction in prayer; we cannot too highly prize the promises of God.
Wherever and whenever we meet in the name of Christ, we should consider him as present in the midst of us. (Matthew Henry Concise Commentary)”