> They don't speak to the amount of mental work that Hans would have had to put in to play optimally (or 'ok' as you say) in those positions.
Yes, they do. When Magnus makes poor choice - not giving himself an advantage or playing moves giving black an advantage - it makes it easier for black. That’s the whole point.
No, that is not how that works. An engine evaluation saying that a position is better for black does not mean that it is easier for a human to play that position. Easy to play and winning for an engine are orthogonal concepts.
Putting your opponent in positions that are better according to the engine but only with engine-like perfect play is a strategy at the highest levels of chess. Because the move is objectively worse, it won't be played, because it's not played, your opponent won't know it, because they don't know it, you'll play it better, then you win.
Yes, they do. When Magnus makes poor choice - not giving himself an advantage or playing moves giving black an advantage - it makes it easier for black. That’s the whole point.