Why do you mention "Nestle 1904"? Nestle did not "copy" any manuscript. Nestle is one of several scholars who has inspected the existing manuscripts and fragments of manuscripts and from that research has compiled that which he believes to be the most accurate representation of the originals.
Your difficulty appears to be with the English translation of a Greek grammatical construct involving HOUDE and EI. You should obtain an introductory Greek grammar and study this matter for yourself.
But you are focusing upon the forest and are not seeing the trees. For the purpose of the Incarnation, Jesus laid aside the attributes of deity, Philippians 2:5-8. During the Incarnation, Jesus functioned as did the Prophets of old, having benefit of the Spirit of God; accordingly, Jesus titled himself the "Son of Man." In Mark 13, Jesus is foretelling the cataclysm surrounding the A.D. 70 destruction of Jerusalem. That cataclysm was a "coming" or "visitation" for the purpose of judgment. In A.D. 70, Jesus himself, resurrected and glorified, returned to execute judgment upon the Remnant of Israel which would not submit to his rule. The parables of Jesus portray the situation; in particular, the parable of Luke 19:11-28 portrays the subjects who would not be governed by the nobleman and their destruction once the nobleman was seated as king.
The precise time at which judgment would fall was known to God the Father alone. Having laid aside the attributes of deity to become man, Jesus himself did not know the time, though in resurrection he would be the one executing upon the physical nation of Israel the sentence of death.
Even in the King James Version, the meaning of Mark 13:32 is clear, except that the use of the word "but" implies "but only" or "with the exception of"; thus, the verse reads:
"But of that day and that hour knoweth no man, no, not the angels which are in heaven, neither the Son, but ONLY the Father."