I have a friend who works in forensics for the police and they say that the worst thing to hinder solving a crime is if there are eyewitnesses. Just because someone gives their account of what they witnessed does not make it fact, so to use eyewitness reports from Dealey Plaza as some sort of argument against the LN theory is ridiculous.
How many people were in Dealey Plaza that day? How many people, with all good intention, described what they saw? How many different accounts were there? How do you decide who is right and who is wrong?
Various survivors of the Titanic gave different accounts of how the ship sank. Some said it sank on one piece where as others stated it snapped in two before going under. That's quite a big thing to differ on.
I remember coming back from a football match one evening and having a heated argument with my friends about whether a player scored a volley with his left foot or right foot. Each of us were convinced we were right.
On Halloween I was walking home and some little spombleprofglidnoctobunss were setting off fireworks in the street. At first I thought the banging noises were coming from behind me. Then it sounded like they were coming from the street to the right of me. Turns out they were actually coming from up ahead of me. My point here is that I couldn't even accurately pinpoint the sound of loud bangs in normal calm surroundings, let alone with people screaming and seeing half of the president's head being blown away.
Desperately clinging on to something like what Frazier said about how Oswald was carrying the bag or how long someone said said they thought it was in order to create an argument is pointless. How about looking at the hard evidence that was actually found on the 6th floor rather than sodding about with unreliable testimonies?
Some interesting (and scientific) reading on eyewitnesses here -
https://www.scientificamerican.com/article/do-the-eyes-have-it/