It does not matter.
The passage in Paul's letter to the Ephesians forms part of his concluding instructions to Christian households, dictating how he believes they should be behaving towards each other. These instructions are inspired by the teachings of Jesus and the scriptures, but are still confined by what is viewed as accepted social conduct at the time. So wives submitting to their husbands and slaves obeying their masters were considered necessary reminders to keep order in this growing community, regardless of the egalitarianism that Jesus taught. If we are to live the example of Jesus with integrity, then this kind of distortion by Paul needs to be recognised and forgiven, not ignored or justified by twisting the meanings of words to suit.
The fact is that honouring someone is not the same as obeying them. There seems to be some confusion by Paul between the two meanings of the verb to honour. The first meaning is to 'regard with great respect', and is in reference to a person or a memory. The second meaning is to 'fulfil or keep', and is in reference to an obligation or agreement. It is this second meaning that can be synonymous with obey, which in reference to a law means to 'comply with'. In reference to a person, however, obey means to 'submit to the authority of', which is not the same as honour.
Yes, it is generally 'right' for children to obey their parents, although there are certainly situations where this could prove harmful to the child, let alone to an adult offspring. Humans are not perfect. So simple obedience isn't what God is asking for here. Remember that in the first commandment we are expected to honour God and to keep his commandments. So in regarding both God and our parents with the greatest respect, we defer to them in our judgements and our decisions, but we obey his commandments. In The Sermon on the Mount (Matthew 5), Jesus then reinterprets these commandments, teaching us that the exact wording of them is less important than the spiritual meaning behind them. Thus 'honour your mother and father' may not be as simple or confining as the words suggest.
The original commandment relates to the problem the Hebrews were experiencing in sustaining the history and the hope of the covenant God had made with Abraham across subsequent generations. The vague hint (not promise) 'that it may go well with you and that you may live long in the land' reflects the hope that they will reap the benefits in the current generation, rather than die there in the desert like previous generations. So in saying 'honour your mother and father', Moses is also saying: respect what your parents and grandparents have explained to you about why we are out here in the middle of the desert living off flat, tasteless bread; honour the journey that began well before you were born, that meant something significant to your ancestors who began it, and that will ultimately reward your descendants; quit whinging about how much harder your life is (you don't know what hardship is!); and you might just get to personally enjoy the rewards that were promised.
The circumstances that led to the specific wording of this commandment may be historical, but the spirit of its teaching is just as relevant today, because the journey it pertains to is actually much larger than the Exodus of the Hebrew nation. It reflects the journey of all humanity through harsh lessons learned and passed on, forgotten, ignored and painfully relearned across many generations. It's easy to get lost in the turmoil of our current existence - to lose our respect for the past, imagining no one else could possibly have had it this hard, or that the better future we're striving to achieve doesn't really exist and everyone is doomed to this 'unrewarding' life for eternity, so we might as well just give up trying. Honouring your mother and father, therefore, is not just about your actual parents, but about honouring human history: learning from it and respecting the efforts made to learn lessons the hard way and pass on the awareness, knowledge and understanding gained from past experiences. It's about honouring the generational link between past, present and future, and recognising that the journey we are on does not begin or end with the present generation.
There is a significant and important difference between obeying the past and honouring it. Every time we get bogged down in adhering to exact wording, traditions and rituals for their own sake at the expense of the spiritual teachings behind them, we have lost touch with this distinction, and then we begin to repeat the mistakes of the past.