If you didn't see anything come off then you don't have flukes. Don't need to dose prazi, cupramine will kill all life except the beneficial bacteria. Meaning if you have worms and pods they will die and so will your coraline.
Looking at your angels there is something else going on unfortunately, does not look like ich in my opinion. But dosing cupramine would not hurt, just make sure to get salifert copper test kit.
Good luck, i know how you feel been there many times and it sucks.
Also, this is what you should have seen from the fw dip. Looks like white sesame seeds.
https://www.youtube.com/watch?v=K3c3XV4jySw