It's a guess based on the shooting script.
I don't think that "now-human" can be interpreted as "not vamp-faced". Human is human. As in "not a vampire".
But when he turns into a vampire the line is used in reference to his face, it doesn't say "turns into a vampire:"
"He turns to her, his face now vampiric." (Quote from the script link'ed.)
Also, Willow says this after now-human Angel walks into the library:
"You can come with us, Angel. Get something to drink. Or, no... don't do that. Just hang out."
And no one says anything to contrast and clearly she believes he is still a vampire. If he became human in the episode there would've been a scene, a short moment,
something to show it happened, he wouldn't just walk into frame suddenly a real boy. The script's narative is the only thing that mentions this, it's not said or aluded to in any way, so I don't know how you think it would've came across on screen which is why I can't buy this.
Sorry, interpret how you will, of course. I just think this is a radical interpretation of the text and was concerned with the way you freely stated that it was a plot point that was dropped because it came across as a fact.