The major problem that arises in the S43:61 is the interpretation of the Arabic word وَإِنَّهُ the English meaning is “And it is” by various translators of the Qur’an.
The Arabic text at S43:61
وَإِنَّهُ لَعِلْمٌ لِّلسَّاعَةِ فَلَا تَمْتَرُنَّ بِهَا وَاتَّبِعُونِ ۚ هَٰذَا صِرَاطٌ مُّسْتَقِيمٌ
Translation at S43:61 by interpretating the Arabic word وَإِنَّهُ or “And it is” (refer to Jesus) are from Sahih International: And indeed, (Jesus) will be [a sign for] knowledge of the Hour, so be not in doubt of it, and follow Me. This is a straight path.
Yusof Ali: And (Jesus) shall be a Sign (for the coming of) the Hour (of Judgment): therefore, have no doubt about the (Hour), but follow ye Me: this is a Straight Way.
The translation above with Jesus’s name in brackets leads to an understanding that Jesus is coming back a second time.
Translations at S43:61 by interpretating the Arabic word وَإِنَّهُ or “And it is” (refer to a knowledge of the hour)
Arberry: It is knowledge of the Hour; doubt not concerning it, and follow me. This is a straight path.
Qaribullah & Darwish: It is the knowledge of the Hour. Have no doubt concerning it, and follow me. This is a Straight Path,
By putting the name Jesus in bracket, the translators are contradicting themselves with Qur’an in several verses which says only Allah knows “The Hour” –
S31:34 Verily the knowledge of the Hour is with Allah alone. It is He Who sends down rain, and He Who knows what is in the wombs. Nor does anyone know what it is that he will earn on the morrow: Nor does anyone know in what land he is to die. Verily with Allah is full knowledge and He is acquainted with all things.
S7:187 They ask you, about the Hour: when is its arrival? Say, “Its knowledge is only with my Lord. None will reveal its time except Him. It lays heavily upon the heavens and the earth. It will not come upon you except unexpectedly.” They ask you as if you are familiar with it. Say, “Its knowledge is only with Allah, but most of the people do not know.”
S33:63 People ask you concerning the Hour. Say,” Knowledge of it is only with Allah. And what may make you perceive? Perhaps the Hour is near.”
S41:47 To him alone is attributed knowledge of the Hour. And fruits emerge not from their coverings nor does a female conceive or give birth except with His knowledge. And the Day He will call to them, “Where are My ‘partners’?” they will say, “We announce to you that there is no longer among us any witness to that.”
Jesus cannot be the sign of the Hour as according to the Qur’an every human will have a taste of death that include Jesus –
S3:185 Every soul shall have a taste of death: And only on the Day of Judgment shall you be paid your full recompense. Only he who is saved far from the Fire and admitted to the Garden will have attained the object (of Life): For the life of this world is but goods and chattels of deception.
S21:34-35 And We did not grant to any man before you, eternity on earth; so if you die would they be eternal? Every soul will taste death. And We test you with evil and with good as trial; and to Us you will be returned.
Jesus is dead and if he is not dead now, he would have known that billions of Christians are worshipping him as God in this world today. But on the Day of Judgment, he is unaware that he was being idol-worshipped because he is dead and the dead man knows nothing of what is happening in this world.
S5:116-117 And when Allah will say: O Isa son of Mariam! did you say to men, take me and my mother for two gods besides Allah he will say: Glory be to Thee, it did not befit me that I should say what I had no right to (say); if I had said it, Thou would indeed have known it; Thou know what is in my mind, and I do not know what is in Thy mind, surely Thou art the great Knower of the unseen things. I did not say to them aught save what Thou did enjoin me with: That serve Allah, my Lord and your Lord, and I was a witness of them so long as I was among them, but when Thou did cause me to die, Thou wert the watcher over them, and Thou art witness of all things.
Thus, the Arabic word وَإِنَّهُ or “And it is” should be a knowledge of the Hour belong to Allah only and it is not Jesus as a sign of the Hour.
Shakir: And most surely it is a knowledge of the hour, therefore have no doubt about it and follow me: this is the right path.
S20:15 “Verily the Hour is coming My design is to keep it hidden for every soul to receive its reward by the measure of its Endeavour.
Pondering with Saifuddin's index 