Quick and very fussy question I'm hoping someone with native-level Japanese could comment on.
My inclination (as a non-native learner) would be to translate 美味しくいただきました as "the staff enjoyed it later". It's both slightly more formal and elegant-sounding than the comparatively coarse "ate", and captures the pleasure implied by 美味しく ("deliciously"). I would expect plain old "ate" if they used 食べました.
Of course, I'm not a professional translator or native speaker! It’s possible I'm over-indexing on the textbook knowledge I have of the language and in practice, to native Japanese eyes and ears, the things I think I'm seeing aren't really there.
replies(6):