I once received an interpretation of tongues which was exactly independently corroborated by the speaker of the tongues whose interpretation matched mine word for word (he did not know mine, I kept it quiet). So really only I, and not anybody else, know it was corroborated to this extent. All revelations are potentially like that, by definition. How did Paul know the revelations he received were true? He was first to receive some of them. No scriptures spoke of them. Hence by definition they were revelations. Revealed but previously mystery. The revelation I received honoured the Lord Jesus Christ without contradicting scripture. This provided further corroboration. Yet sometime it is not so easy, especially if it does not mention Jesus Christ. You have to know scripture, but your hands are tied if your faith limits what scriptures you know. They might not cover the same area as the revelation covers. Other scriptures outside your denominational canon might cover it, unbeknown to you. That was the case with the revelation I received. I found it was in scriptures outside the canon I was brought up with, only because I was looking for a certain Bible version, the Septuagint interlinear, only sold in a bookshop for other denominations, and a book of scriptures I had never know existed caught my eye and I leafed through it and saw straightaway many verses similar markedly to the revelation words. I found the scripture concerned was quoted in the NT. So this greatly encouraged me. Being too blinkered is not ideal when it comes to genuine revelations.