"I think a committee of individuals comprised of both principled adults and emancipated youths would be far more likely to render an impartial decision"

If they are principled, then they are partial, not impartial.

"When I say state, I'm not talking about a judge, whom I admit would be almost as likely as a parent to make a decision based on personal feelings rather than objective evaluation. "

Judge tends to be the best the State can come up with. Based, naturally, on the personal feelings on the voters, as written into laws, training of judges and recruitment of judges.

There have been various approaches as to the personnel of a court of law:
A lone professional judge ruling from the bench (the habitual approach of common law);
a jury forcibly drafted from peers (another habit of common law)
a committee of several professional judges (very rare in common law, more common in civil law)
lay judges who unlike common law juries sit and vote with professional judge/s
semiprofessional justices of peace, either alone or in petty or quarter sessions

So what kind of committee could best deal with disputes between parents and children?

In terms of community support, how about a jury of parents? That´s the best in terms of gaining community backing to the judgment, and of being seen as impartial by the parents and children - a group of other parents telling the parents in question that they treat their own children differently and the parents called to the jury should listen to their children and change their ways.