But Artemis II launched during passover - so a day before the full moon. That means that for a 10 day mission, the flyby will be four days after the full moon. And the flyby is necessarily on the far side of the moon, that's how physics works. So they'll be passing over the far side of the moon four days after a full moon - the far side of the moon will be in almost complete darkness. Not even Earthshine lights the dark side of the moon when it is full.

My understanding is that even that small amount is more than the Apollo crews had. It's all a bit of a marketing line anyway. We can see a good portion of the "far side" from Earth due to the Moon's libration.

Still, it's true that parts of the far side are still unseen by human eyes (if you consider pitch black landscape to be "unseen" which I think is fair given the lack of any significant illumination as you point out).