Okay, that really *is* an interesting question. I hadn't previously realized how interchangeable "coriander" and "cilantro" are on the other side of the pond. And it turns out that in Charles Perry's "Medieval Arab Cookery", he consistently uses "coriander" for both, although with different tweaks of phrasing.

As it happens, though, in this edition, they are explicitly making the distinction -- see the Glossary, and note that "cilantro" does appear in some recipes.

That said, this translation was the work of many hands, so it is possible that there could be inconsistencies. So I can't be certain...