Will God hold accountable the two thieves who had not reached puberty for their theft, and is the one who was stolen from entitled to take from their good deeds or have some of their sins borne by them on the Day of Resurrection if they do not return the stolen goods?

Those who stole from you when they were young are not sinful because the pen is lifted from them. If they died before reaching puberty, you will not take from their good deeds, nor will they bear any of your bad deeds. However, if they reached puberty and did not return your right, then they are sinful, and your right remains their responsibility. You will then take from their good deeds, or they will bear some of your bad deeds. Even though the pen is lifted from a child, the responsibility for what was stolen does not fall away from them. The general principle is that the wronged person takes from the good deeds of the wrongdoer, or the wrongdoer bears some of the bad deeds of the wronged person. However, Allah may compensate the wronged person from His bounty without taking from the good deeds of the wrongdoer, especially if the wrongdoer repents sincerely and is unable to return the right. A complete repentance includes the wrongdoer compensating the wronged person. If they do not compensate them in this world, then compensation is inevitable in the afterlife. Therefore, the repentant wrongdoer should accumulate many good deeds. There are hadiths and narrations indicating that Allah Almighty may satisfy the disputants on the Day of Judgment from the treasures of His bounty, as in the hadith of the Prophet's supplication for his Ummah, and Al-Ghazali's statement that Allah satisfies the disputants from the treasury of His bounty if He knows the sincerity of His servant. We advise you to forgive and pardon, for whoever forgives and reconciles, their reward is with Allah.