Is the disobedience of children to their parents considered a divine punishment for previous parental disobedience, and will the disobedient child be held accountable for that, or does the matter fall under the category of tribulation?

It is not necessarily the case that the reason for children's disobedience to their parents is the father's disobedience to his own parents. The father may be dutiful, yet be punished by the disobedience of his children due to his shortcomings in their upbringing, or due to other sins he committed, or it could be a trial from Allah. Children must obey and treat their parents kindly, even if they are disobedient or non-Muslim, unless they command an act of disobedience.