That is nicely done and very sweet, though it looks like the artist was mostly inspired by the 2005 film for how Lucy looks. (To be fair, Pauline Baynes herself never got Lucy's hair colour right either — we're told at the end of LWW, as well as later on in HHB, that Lucy is golden-haired!! )

I'd be more concerned that the portrayal of Lewis doesn't look quite like him, but we don't quite see his face clearly and at least one can tell who he's meant to be.   That and the fact that although Lewis-as-narrator does indicate in VDT that he's met Lucy in person, it's implied that that was in our world. But it is sweet and magical to imagine them meeting in Narnia. Perhaps — especially with what Lucy is saying — the artist is meaning to suggest that this is after Lewis's death and he's entered Aslan's country via the real Narnia?? That's a lovely thought.