I appreciate that EYB uses cross-references so that my search for "arugula" also brings up Australian recipes with "rocket" (for example).
Also, when I have cooked a recipe which uses the unfamiliar term, I always write a note in the book with the term I use. And I make a note in the book's index that [arugula] = [rocket]. I also make notes for sizes (converting centimeters to inches for baking pans) and temperatures (gas marks/Celsius to Fahrenheit) in the recipe instructions.
I greatly appreciate cookbook authors and publishers who use both metric & English measurements in their recipes. And several of my Australian cookbooks use both the Australian English and American English vocabulary in their ingredients lists. In today's international publishing environment, these practices should be standard!