Lightroom Black & White conversion presets and auto mix (automix) vs. panchromatic film

IIRC panchromatic film was so called not because it was objectively "correct" in some way, but more because it dealt with the subjective shortcomings of other emulsions - most particularly, orthochromatic film's tendency to show little tonal contrast with particular hues (such as, the contrast of someone's lips vs their face) that the human eye does distinguish easily as contrasting tones - and that we find it especially important to distinguish in terms of facial expression etc.

So early makeup for movies consisted of green lipstick etc, rather than red: the film stock being too "slow" for corrective filters to be practicable.

Perhaps we might stretch the words "correct" or "accurate" to mean: producing a similar result subjectively, as human vision might.

However human vision is notoriously varied between people; also variable and adaptive for a single person in different circumstances; also heavily dependent on non-optical processing within the nerves and brain.

A good illustration of how RGB processing differs from processing that separates tone and hue, comes when you lighten or darken an image using Tone Curve vs the Basic panel adjustments. Watching what happens to the saturation of the different hues as you do this.

LR's standard B&W conversion builds in some target assumptions that are not so different from those relied on for panchromatic B&W film, because serving the same practical ends, and the same aesthetic, within the same cultural traditions. Of course you can widely alter these to suit your own intent, the same as when using a colour filter over a mono emulsion.

Personally I prefer LR to remain in colour mode even for a B&W-intent image, which I do by fully desaturating all the colour ranges in HSL. This leaves every colour adjustment still live and effective - whereas taking the image into B&W mode switches off some of those, in favour of a simplified set of tone response sliders. Furthermore, if going into PS I tend to do so still as a colour image and then apply B&W processing only onto the round-trip version once back in LR. This permits multiple virtual copies to play around with varying B&W conversion options, as well as with other matters in response to those conversions, all non-destructively.