They cite one of the works of Gert Smolka (Smolka and Panangaden, 1985), who was the original creator of Oz. But I agree that Van Roy and Haridi did a lot of research on functional logic programming back in the 1990s that seems to be ignored here.

When I worked on program semantics, I had the impression that PLT communities in the US and EU tend to ignore each other. This also translates to education. CTM is an epic book, and very readable, but I don't think it's well known or used much on the other side of the pond.