Probably bears repeating that I don't think it's too productive to get too far into the weeds on these issues without looking back at the big picture.
It seems to me that the big picture is that Epicurus is saying that Nature equips us with faculties through which we can make sense of what is going on around us, and that those faculties operate naturally and are not divine or prophetic or inherently deceptive in nature. Using those faculties we can make sense of many things within the flux and we don't have to throw up our hands and give in to radical skepticism. We also don't have to worry that there is some divine or ideal or true world to which we can get access only through revelation or esoteric logical maneuvering.
As far as the details of what those faculties are and how they operate, some of that is obvious (that the senses are honest but don't constitute truth in themselves - we have to evaluate the data to decide what we think is true) and some of it is less obvious (that the mind can be influenced by things other than the 5 classic senses - which is where the images apparently come in as a proposed explanation).
I certainly think there can be lots of varying positions and disagreements about how to get into the details of how these faculties operate, and that's largely a matter of advancing scientific knowledge that we gain through better technology. But the bigger picture that all this is natural simply gets clarified in details by the advancing technology, it doesn't get reversed or called into serious question.