Translating ingredients, American versus English
I'm new to this, but in the first three articles Duolingo has presented to me, two were recipes, and several ingredients are commonly sold in the US with their Spanish names. I'm pretty sure if I asked my grocer for fresh coriander, he wouldn't know what I was talking about, but they have lots of cilantro.
What's the preference? This could get very weird with things like crema for which the closest english equivalent is french...creme fraiche.
Recipes pose an interesting case. Like with translating any article, they key is convey the information from one language to another in a clear and effective way. So when translating recipes, the goal should always be to provide enough clear information so that someone who reads it in the target language could successfully replicate the recipe in their home/restaurant.
So at times, you will need to add some extra information. So in your case, if you translate 'una taza de cilantro picado' in Spanish, you could translate it as 'one cup of chopped cilantro/coriander leaf' or 'one cup of chopped coriander leaf (cilantro). This allows both common English forms to be displayed so that it will be clear to a wide audience.
Somethings, one needs to add even more information. To use another Spanish example (as you are learning Spanish), gelatine dessert recipes in Spanish often call for 'cola de pescado'. For example, 'añadir 6 gramos o 5 hojas de cola de pescado por litro'. Now I have seen cases on DuoLingo where people simply translate this as 'add 6 fishtails' even in a chocolate mousse recipe ;-) These are actually thin gelatine leaves made from fish swim bladders that one dissolves in water. They look like thin fish scales or tails, and thus the name.
When I translate "'añadir 6 gramos o 5 hojas de cola de pescado por litro', this is what I would do ''Add 6 grams or 5 fishtails per litre ['holas de cola' or fishtails are thin gelatine leaves sold in packets, common in Spain, you can substitute packaged gelatine leaves or isinglass]. By adding the explanatory note in big brackets, you provide the needed information for the reader to successfully make the recipe. Translators often use explanatory notes, offset by brackets, in situations like this. Otherwise you may end up with a chocolate mousse full of fish tails which would not be terribly pleasant for your family or guests ;-).
Hope this helps!
From a cookbook: In the United Kingdom, we would refer to the leaves and stalks of the plant as "coriander" and to the seeds as "coriander seeds": the word "cilantro" does not exist. In the United States, I now know that the leaves and stalks of the plant are referred to as "cilantro," while the seeds are referred to as "coriander."
I'd add that 'crema,' from my experience, is simply 'cream' unless further modified -- crema acida = sour cream, for example. 'Nata' is another word for cream.