the recording makes the word sound like λάχανι, with the stress on the first syllable. Does the recording sound natural to the native speakers?
λαχανί translated as light green here. It is not a scientific name, you cannot use the word λαχανί in a Physics lecture for instance, unless you want this lecture to be more cheerful and fun. Never! Ανοιχτό πράσινο, yes. Λαχανί is a word for clothes mostly.
Λαχανί is introduced in the lesson's notes as "cabbage green", so why isn't that an acceptable answer?
In this case the best translation is: "light green" = "ανοιχτός πράσινος" - But Stergi3 already wrote this about one year before! (2018/07/04)