Translations are translations! they are not the originals. If you want to see what was actually written, go back to the original language. and the YLT and LSV you cite as literal translations are not literal byt dynamic. for "having" does not appear at all.
According to Strong's:
erchomai
er'-khom-ahee
Middle voice of a primary verb (used only in the present and imperfect tenses, the others being supplied by a kindred [middle voice] word, ἐλεύθομαι eleuthomai or ἔλθω elthō; which do not otherwise occur); to come or go (in a great variety of applications, literally and figuratively): - accompany, appear, bring, come enter, fall out, go, grow, X light, X next, pass, resort, be set.
So I don't think that it is referring to a future coming back. The Cambridge Bible notes says of verse 2:
The sentence may be taken in more ways than one: (1) as both A. V. and R. V.; (2) more accurately, and with some difference of meaning; confesseth Jesus Christ as come in the flesh; (3) confesseth that Jesus is the Christ come in the flesh. Remark that S. John does not say ‘come into the flesh’, but ‘in the flesh’: Christ did not descend (as Cerinthus said) into an already existing man, but He came in human nature; He ‘became flesh’. Moreover he does not say that the confession is to be of a Christ who came (ἐλθόντα), but of a Christ who is come (ἐληλυθότα). This ‘coming’ is not an exhausted fact: He is come and abides in the flesh.
Albert Barnes' notes says:
That Jesus Christ is come in the flesh - Benson and some others propose to render this, “That Jesus, who came in the flesh, is the Christ.” But this is liable to serious objections.
(1) It is not the obvious interpretation.
(2) It is unusual to say that Jesus “had come in the flesh,” though the expression “the Son of God has come in the flesh,” or “God was manifested in the flesh,” would be in accordance with the usage of the New Testament.
(3) This would not, probably, meet the real point in the case. The thing denied does not appear to have been that Jesus was the Messiah, for their pretending to be Christian teachers at all implied that they admitted this; but that the Son of God was “really a man,” or that he actually assumed human nature in permanent union with the divine. The point of the remark made by the apostle is, that the acknowledgment was to be that Christ assumed human nature; that he was really a man as he appeared to be: or that there was a real incarnation, in opposition to the opinion that he came in appearance only, or that he merely seemed to be a man, and to suffer and die. That this opinion was held by many, see the Introduction, Section III. 2. It is quite probable that the apostle here refers to such sentiments as those which were held by the “Docetae;” and that he meant to teach that it was indispensable to proper evidence that anyone came from God, that he should maintain that Jesus was truly a man, or that there was a real incarnation of the Son of God. John always regarded this as a very important point, and often refers to it, Joh_19:34-35; Joh_20:25-27; 1Jn_5:6. It is as important to be held now as it was then, for the fact that there was a real incarnation is essential to all just views of the atonement. If he was not truly a man, if he did not literally shed his blood on the cross, of course all that was done was in appearance only, and the whole system of redemption as revealed was merely a splendid illusion. There is little danger that this opinion will be held now, for those who depart from the doctrine laid down in the New Testament in regard to the person and work of Christ, are more disposed to embrace the opinion that he was a mere man; but still it is important that the truth that he was truly incarnate should be held up constantly before the mind, for in no other way can we obtain just views of the atonement.