The exaggerated gain of 144,000 total experience is an exaggeration and assuming they all hit a skill with passion, since the multiplier for other skills is 35%, a baby growing from 0 to 18 would never gain passions so no I could never win 8000, that's only for children over 13 who already have their maximum passions, but they could only be in growth vat 5 years (15 days) that is 8,000x5=40,000. If a child, as the wiki text says, spends the full 54 days, he would never gain passions, so he would only increase 2,800 (8000x35% no-passion skill), and therefore, after 54 days, he could never gain that amount of experience. Babies are not born with passions, unless they have some specific hereditary gene as in the case of the Yttakin, Great animals. But babies from 0 to 3 can only gain experience in shooting, melee and social. That's why a boy from Cuba would really be useless, after all, but you would have 1 adult of 18 in less than a year, and all the abilities fairly uniform, he would have 6 abilities at level 2 (almost 3 for being 5600 exp ) and the other 6 skills at level 1 (almost 2 for being 2800 exp)
some calculations
5,600x6=33,600 2,800x6=16,800 33,600+16,800=50,400
That is why the change from 144,000 to 50,400 is necessary.
If you were lucky that they all went up to any of the first 3 skills, shooting, mele or social, they would reach level 9 halfway to reaching 10 If the child was born with passions that should be possible with mods, it would be something else.