From a Christian perspective, your question contains two erroneous premises: first that every person will be saved (universal salvation) and second that “Jesus descended into the deepest depths of Hell to endure further ineffable tortures.” According to the Bible, only those persons who come to saving faith in Christ Jesus will be saved.
God is certainly full of love and mercy; it was these qualities that led Him to send His Son, Jesus Christ, to earth to die on the cross for us. Jesus Christ is the exclusive door that leads to an eternity in heaven. Acts 4:12 says, “Salvation is found in no one else, for there is no other name under heaven given to men by which we must be saved.” “There is one God and one mediator between God and men, the man Christ Jesus” (1 Timothy 2:5). In John 14:6, Jesus says, “I am the way and the truth and the life. No one comes to the Father except through me.” John 3:16, “For God so loved the world that he gave his one and only Son, that whoever believes in him shall not perish but have eternal life.” If we choose to reject God’s Son, we do not meet the requirements for salvation (John 3:16, 18, 36). Source: https://www.gotquestions.org/universalism.html
The place Jesus went to after his death was not a place of torment or torture. Jesus’ suffering ended the moment He died. The payment for sin was paid. He then awaited the resurrection of His body and His return to glory in His ascension. Did Jesus go to hell? No. Did Jesus go to sheol/hades? Yes.
Some have the viewpoint that Jesus went to “hell” or the suffering side of sheol/hades in order to further be punished for our sins. This idea is completely unbiblical. It was the death of Jesus on the cross that sufficiently provided for our redemption. It was His shed blood that effected our own cleansing from sin (1 John 1:7–9). As He hung there on the cross, He took the sin burden of the whole human race upon Himself. He became sin for us: “God made him who had no sin to be sin for us, so that in him we might become the righteousness of God” (2 Corinthians 5:21). This imputation of sin helps us understand Christ’s struggle in the garden of Gethsemane with the cup of sin which would be poured out upon Him on the cross. Source: https://www.gotquestions.org/did-Jesus-go-to-hell.html
As far as the argument of Cosmic or Celestial Child Abuse goes, below is a link to a U.K. 2004 article that soundly exposes the error of the claims made by Steve Chalke. Part of the article says this:
Steve Chalke is caught in a contradiction. He wants to affirm God’s anger in some sense, but is intent on redefining God’s holiness and downplaying the seriousness of sin (p. 173). Nevertheless it is right to say that anger is a legitimate expression of God’s love. Because the Lord is righteous He loves righteousness and hates the wicked (Psalm 5:4-5; 11:5, 7). The Bible speaks plainly about God’s anger against all sin being expressed in the present and at the day of judgment (Rom. 1:18ff, 2:5-11; Eph. 5:3-6).
God’s love is not a moral weakness. If sin ought to be punished then there is nothing in God that impels Him to leave it unpunished. If God loves sinners then some way must be found for His justice to be satisfied as well.
Where Wrath and Mercy Meet: Is it true that penal substitution contradicts the statement that God is love? If it is then the New Testament writers were not aware of it. Paul tells us that the God who justifies those who believe, by his grace, does so by setting forth His Son as a propitiation (Rom. 3:25). The writer to the Hebrews says that it was as a merciful High Priest that Jesus made propitiation for the sins of the people (Heb. 2:17).
The apostle John tells us that God is both light (1 John 1:5) and love (3:16). ‘In this is love’, writes John, ‘not that we have loved God but that he loved us and sent his Son to be the propitiation for our sins’ (4:10). On the basis of this wrath-averting death Jesus acts as our advocate with the Father when we sin (2:1-2). Rather than being incompatible with love, God’s love saves sinners from His own wrath through the death of Christ (Rom. 5:8-9).
By pitting Jesus’ teaching about not ‘repaying evil for evil’ against the idea of penal substitution Steve Chalke makes a basic but telling mistake. Consider Romans 12:17, 19: ‘Repay no one evil for evil… Beloved, never avenge yourselves, but leave it to the wrath of God, for it is written, “Vengeance is mine, I will repay, says the Lord”‘. Retribution belongs to the righteous Judge not to private individuals. But the state is given the limited remit to punish wrongdoers, ‘For he is the servant of God, an avenger who carries out God’s wrath on the wrongdoer’ (Rom. 13:4). Source: https://banneroftruth.org/uk/resources/articles/2004/a-scandalous-attack-on-the-cross/
That is one Christian refutation to the accusation that God is guilty of “child abuse” with regard to his Son. Bear in mind that nobody forced Jesus to lay down his life for us. He did so willingly:
The reason my Father loves me is that I lay down my life – only to take it up again. No-one takes it from me, but I lay it down of my own accord (John 10:17-18).
As Cerulean Chelonii pointed out, because Jesus is part of the One Being of God, fully man and fully God, it was God who took the punishment we deserve upon Himself. Such love!