Well of course, in that case these boys would be on their way to a lifetime of hell, even though just as innocent. Lawyers for the 8 year old boy said that police fabricated the confession. In other words, they charge that the boy never did confess, and the police just made it up. Lawyers for the 7 year old boy said that police pressured him into agreeing to things that weren't true. As we see in this case, they are not reliable at all.
Police can use any pressure tactics they want to get people to do what they say.
These tactics often work even on adults. If they want to place the child in a room without toys, and make him fear he will never go home until he says the right thing, and subject him to endless sessions of unwanted conversation with adults trying to manipulate him, they have the legal right to do so. If they want to bribe a child with candy or a toy, or punish him with isolation, or if they want to confuse him with lies, all that is acceptable too. Certainly no American court will interfere. And, if the child still somehow refuses to confess, you can just lie and say he confessed anyway.