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This answer to Why are these astronauts green? explains the new (now about 2 years old) solid state (LED) lighting modules being added to ISS interior lighting, replacing the fluorescent lights (see this and this answer).

In video links from the ISS I've only seen neutral white illumination.

  1. Have the astronauts settled on a white or near-white setting (as measured by a meter, our eyes and brains constantly move our personal white-point around) or do they like to operate in Dreamliner mode (also here) and modulate the color of the lighting regularly, depending on "time of day" or some status?

  2. Have there been any health-related directives on recommended color settings, or colors to avoid?

From this answer:

color LED lighting in the ISS color LED lighting in the ISS

These pictures are from ISS crew member Jack Fischer's twitter account.

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    $\begingroup$ I would guess they simulate the natural change of daylight color on earth(dawn, noon, dusk). Different tones of white do have different influences such as making tired or awake or drastically changing the appearance of food and therefore influencing appetite. But I couldn't find any sources which talk about the configuration on the ISS. $\endgroup$
    – GittingGud
    Jul 12, 2019 at 5:34
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    $\begingroup$ If I was there, I would totally hack up a Christmas light display. Or other national holidays. Guidelines be damned. Good for morale. $\endgroup$
    – smci
    Jan 7, 2020 at 10:00

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Pretty much as my answer to a related question:

As part of the experiment, the crew of the ISS are subjected to the Dynamic Lighting Schedule:

  1. Have the astronauts settled on a white or near-white setting ?

Yes:

Pre-programmed and pre-planned with 3 lighting values:

Three pre-determined light settings are envisaged for use in different operational settings. Specifications for Correlated Color Temperature (CCT) and luminance in candelas (cd) settings:

  1. a General Illumination setting - 4500 K white light, 210 cd.
  2. a Pre-Sleep setting - 2700 K (blue-depleted) white light, 90 cd or ideally lower.
  3. a Phase Shift/Alertness setting - 6500 K (blue-enriched) white light, 420 cd.

As you can see, its pretty much a variation on white...

Those green-tinted pictures seem to be system LED unrelated and might just be them having fun with cameras and remote strobe/gels.

  1. Have there been any health-related directives on recommended color settings, or colors to avoid?

I think it is less about avoiding colors and more about regulating the timing of the blue emanation from said light sources.

“While the multi LED system can provide millions of different light spectra, we plan to use three settings for now,”

“A high-quality daytime light to help the crew see well, a higher intensity blue-enriched light to boost alertness or shift circadian rhythms, and a lower intensity blue-depleted light before sleep.”

controlSSLA

https://www.nasa.gov/mission_pages/station/research/experiments/explorer/Investigation.html?#id=2013

https://www.nasa.gov/mission_pages/station/research/experiments/explorer/Investigation.html?#id=640

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