Hi there, at the moment, yes the artwork is all official art or by official artists, that is for example Charlie Bowater as she has done several commissions for Sarah J. Maas and also participated in the ACOTAR official coloring book, but some of the art she has done is fanart, as she started doing fanart before Sarah hired her and has also done fanart pieces on her own such as this one which is fanart, but since her artwork greatly resembles the official pieces, it is allowed, same goes for CJ Merwild aka Coralie Jubenot, she has done official pieces for special editions of ACOTAR but also fanart, her fanart is allowed as it greatly resembles the official depictions of the characters.
Now as for morgana0anagrom, she has done 2 official pieces (that is they're officially licensed) this one and this one, all the rest of her work is fanart. Her fanart pieces were indeed on the wiki in the past, because we used to allow fanart but the policies changed due to some things that occurred and we currently only allow official artwork, exceptions currently being Charlie Bowater and CJ Merwild. As a side note, officially licensed means the pieces are licensed through Sarah J Maas and her agent, meaning she has approved of them.
Edit: I forgot to clarify about the images of the ACOTAR official coloring book on character pages, the colored versions are not official as in they are colored by fans, but the artwork in it it's official from the coloring book, but being a coloring book the pages come without any color in them.