OK I am trying to keep not only the big picture but also just the thread title in focus as we go forward. The issue under discussion is broadly speaking (I think) whether "concepts" as that word is commonly used are a part of the Epicurean canon of truth.
Some translators seem to take that position (that "concepts" are part of the canon of truth), but I think it is fair to say the majority (and those I personally find most persuasive) do not take that position. They think Epicurus was referring to something pre-rational, potentially "intuitive," that functions in parallel (and analogously, I think it is fair to say, as pre-rational) with the five senses and with the pleasure/pain mechanism.
So I think I am reading the Feldman-Barrett comments to say that she also agrees that there is a pre-rational mechanism going on that pre-exists in the sequence of things before the arisal of what we might call "the concept of fear."
If I am reading that correctly that that makes FB a useful data point in supporting Epicurus' contentions and explaining them as part of Epicurean philosophy.
(?)