It's much more difficult than it used to be, but I think there is still some value to human guidance, more as a "referee" than anything else.
Right now we have essentially two top tier engines -- traditional brute force with alpha beta pruning (stockfish), and ML (leela). Both alone are incredibly strong, but they are strongest and weakest in different types of positions. A computer chess expert, who knows what kind of positions favor stockfish and what kind favor leela, could act as a "referee" between the two engines when they disagree, and when they are unanimous, simply accept the move.
Ten years ago, a grandmaster driving a single engine could typically beat an equal strength engine. I don't think that's the case anymore.
But I think if you have someone who is an expert at computer chess -- not so much a chess grandmaster, and you gave them Leela AND SF, and let them pick which one to use when in the case of conflicts -- they would score positive against either leela or stockfish in isolation.
Larry Kaufman designed his new opening repertoire book by doing exactly this -- running Leela on 2 cores + GPU, and stockfish on 6 cores, and doing the conflict resolution with his own judgement.
The human can certainly no longer pull his own moves out of thin air, though.
Computer mastery of Go has reached the point where it is a difficult task for an expert (read: grandmaster level) human to even follow what is happening. It is totally implausible that a human could resolve a conflict between top engines in a meaningful way.
It is unlikely that Chess is any different. Any superficial understanding by a human of which move is 'better' is just ignorance of the issues around evaluating a position. If you have statistical evidence that is something. 'But I think' is not evidence.
It might be entertaining to have a human involved. It isn't going to help with winning games.
I can't speak for Go but in Chess the best players in the world understand the nuances of a position still better than the computer engines and - if occasionally proven wrong by the computer analysis - are able to understand the refutation and refine their strategic eveluation. I know this because it's what I've been doing in the past seven years in the realm of correspondence chess to gain the title of international master.
I don't even know the rules of Go, but I am a long-time chess enthusiast, and I have a decent, but not top-level, understanding of chess (I am a FIDE master and I also play correspondence chess (which is human+engine) and have an interest in computer chess heavily).
I can absolute guarantee you that a human (who is an expert in computer chess, someone like Larry Kaufman) + engines will beat a single engine over the long run. With current tech and computing power, this is ONLY because we have brute force (with alpha-beta pruning) and ML engines that are at near-equal strength, and have strengths and weaknesses in different types of positions, and that those strengths and weaknesses are understandable.
If we did not have AlphaZero, I don't think the human would be able to add anything at all currently.
I can't imagine a human doing anything besides making things worse or even.