Would it be possible to have the 'faceless' tag be reserved only for characters that are actually lacking a face, as opposed to the face simply not being visible? 'Faceless character' adequately covers the latter, though I think 'obscured face' would be more accurate.

Would "actually lacking a face" be different from featureless_face?

Are you suggesting that all the faceless_* tags keep their current usage, and just faceless used to mean "actually lacking a face"? That seems confusing. I admit using faceless_* for a character whose (presumable) face is offscreen isn't intuitive either but at least it's internally consistent.

faceless being characters whose faces aren't visible better matches the actual usage (see: phrases like "faceless hentai protag"), and featureless_face being characters who don't have one matches the other "featureless" tags like featureless_breasts.

The faceless_* tags could use some clean up, a lot of featureless_face characters are probably added to it by people unaware of the featureless_face tag.