You are confusing self attesting and self authenticating.
Self authenticating is what the Muslims do, it's what tyrants do, it's what stubborn men do. It says "I'm right because I say I'm right."
Self attesting is when the scriptures manifest themselves to be the Word of God because God himself attests to them in Creation, Providence and in redemption. In Creation and Providence via general Revelation. In redemption via special revelation.
5. We may be moved and induced by the testimony of the Church to an high and reverent esteem of the holy Scripture;a and the heavenliness of the matter, the efficacy of the doctrine, the majesty of the style, the consent of all the parts, the scope of the whole (which is to give all glory to God), the full discovery it makes of the only way of man’s salvation, the many other incomparable excellencies, and the entire perfection thereof, are arguments whereby it doth abundantly evidence itself to be the Word of God; yet,
notwithstanding, our full persuasion and assurance of the infallible truth, and divine authority thereof, is from the inward work of the Holy Spirit, bearing witness by and with the Word in our hearts.b
a.
1 Tim 3:15. • b.
Isa 59:21;
John 16:13-14;
1 Cor 2:10-12;
1 John 2:20,
27.
Jesus made this same speak to the witness of the Spirit in John 8.
18I am one that bear witness of myself, and the Father that sent me beareth witness of me.
19Then said they unto him, Where is thy Father? Jesus answered, Ye neither know me, nor my Father: if ye had known me, ye should have known my Father also.
And in 1 John 5...
9If we receive the witness of men, the witness of God is greater: for this is the witness of God which he hath testified of his Son. 10He that believeth on the Son of God hath the witness in himself: he that believeth not God hath made him a liar; because he believeth not the record that God gave of his Son. 11And this is the record, that God hath given to us eternal life, and this life is in his Son. 12He that hath the Son hath life; and he that hath not the Son of God hath not life.
This appeal to the work of the Holy Spirit is all we have and it is all Jesus ever had and it is all there ever is and ever will be.
Finally... Paul didn't outline the transcendental argument but he used it. In Romans when he asserts that "God has made himself known so that they are without excuse." That is an appeal to the attestation of God in nature via General Revelation.
There is a difference between self authenticating and self attesting.