In most Western Christian churches, the 'Trinity' is comprised of three eternal figures: Father, Son, and Hoily Ghost. The so-called 'Sabellian fallacy appears to me to resolve a major philosophical problem, that humankind did not exist before the 6th day of Creation.

During the time before the Creation of Man per se, how could Jesus exist if there were no men? And how could the Holy Spirit exist without any people with whom to form an individual connection?

Some Western churches do not accept the existence of a Trinty, but none go as far as 'Modalism,' which refers to the three figures in the Trinity not all existing simultaneously. The Eastern church takes a slightly different view. The 2nd Nicene Council of 7, now renamed the Council of Constantinople, did not specify the Trinity as eternal in its version of the Nicene creed, which is the accepted origin of the creed in the Eastern Orthodox church. But later counselors did, so in traditional Eastern Orthodox theology, the Trinity is also comprised of three equally eternal figures:

Eastern Orthodox Christians believe in a single God who is both three and one (triune); the Father, Son, and Holy Spirit, "one in essence and undivided". The Holy Trinity is three "unconfused" and distinct divine persons (hypostases), who share one divine essence (ousia); uncreated, immaterial and eternal. The Father is the eternal source of the Godhead, from whom the Son is begotten eternally and also from whom the Holy Spirit proceeds eternally. The essence of God being that which is beyond human comprehension and cannot be defined or approached by human understanding. — https://en.wikipedia.org/wiki/Eastern_Orthodox_theology

However, at least according to conventional ideas of time, the Son and Holy Spirit could not have logically existed before the Creation of Man. Is the traditional Western and Eastern creed that the Trinity is eternal therefore a philosophical fallacy?

There is an alternate view in Eastern Gnosticism, which accepts what is now called 'the Sabellian fallacy.' As Eastern Gnosticism is accepted in the Eastern Orthodox church, it states the following, although all orthodox theologians, including the Eastern ones, throw up their hands in horroe

The Greek Orthodox teach that God is not of a substance that is comprehensible since God the Father has no origin and is eternal and infinite. Thus it is improper to speak of things as "physical" and "metaphysical"; rather it is correct to speak of things as "created" and "uncreated." God the Father is the origin and source of the Trinity of Whom the Son is begotten and the Spirit proceeding, all Three being Uncreated.[43] Therefore, the consciousness of God is not obtainable to created beings either in this life or the next (see apophatism). Through co-operation with the Holy Spirit (called theosis), Mankind can become good (God-like), not becoming uncreated, but partaker of His divine energies (2 Peter 1:4). From such a perspective Mankind can be reconciled from the Knowledge of Good and the Knowledge of Evil he obtained in the Garden of Eden (see the Fall of Man), his created substance thus partaking of Uncreated God through the indwelling Presence of the eternally incarnate (Phil 3:21) Son of God and His Father by the Spirit (John 17:22-24, Rom 8:11,16-17). — https://en.wikipedia.org/wiki/Sabellianism

Whereas the Sabellian view is heretical by Eastern Orthodox views, in it the Holy Spirit and Son were 'products of the uncreation,' and therefore would have come into existence sometime after the Sixth Day, thus resolving the first stated paradox. So is the Sabellian fallacy actually a theological fallacy, or is it actually a philosophical resolution of the Trinity's 'eternal three' fallacy?

Cheers ) Ernest