Perhaps she was referring to Neville? Although, he really had improved since DA days.

I agree that the UK child and adult covers are much better than the US cover. I think the US cover is Harry and Voldermort in the final chapters, with Hogwarts rubble around them. The sun comes up at the final critical point, and I think that is what it is depicting.

Page 743
"A red-glow burst suddenly across the enchated sky above them as an edge of dazzling sun appeared over the sill of the nearest window. The light hit both of their faces at the same time, so that Voldermort's was suddenly a flaming blur."