Before treating, did you remove anything from the filter (Polyfilter, activated carbon...) which would absorb the copper? Did you begin doing frequent water changes and put something back into the filter to remove the copper and some of the ammonia the fish are producing when treatment was done?

Finrot is a bacterial infection spreading, aided by dirty water and stress. Ich is often produced by stress - among the more common causes of stress is dirty water. Temperature drops are also responsible for Ich outbreaks. If you don't mind adding 1/3 doses of the medicine and salt with each water change, can you save and treat some water today and do a 1/3 water change tomorrow. Save and treat enough water for the next day and do that for several days until the fins heal and the Ich goes away. Some fish may die; remove the bodies at once!

I'm not sure what point there is to cleaning plants if you are going to put them right back in the tank. And moving them and the fry to another tank, unless it is larger and more accessible, seems just like infecting another aquarium.

Oh! You mean Ich babies as in the mobile stage of the Ich. If you were sterilizing the plants in the tank, you'd kill all of the fish. By the way, copper will retard the development of plants and kill many of them over time if it is left at a medicinal level.

There are several combinations of medicinal dyes, which properly administered, along with walking the temperature up to about 80F, doing those water changes, feeding carefully and adding maybe a level tablespoon of salt per five gallons can do in the Ich. But you need to get going now. And you need to treat for the time period the treatment's directions recommend. It should command. ;)

I'm unclear if the Coppersafe is still in the tank. When a person treats for something, at the end of the prescribed period you get that stuff out. (God forbid, but if you had to take Chemotherapy you wouldn't continue it indefinitely.)

There is a ton of stuff on Ich in Immediate Help. You would have helped yourself and your fish to have checked that and begun treatment sooner.

Oh, and treat the plants along with the rest of the tank. Your Val may die down to the roots, but if the roots are white, it will grow back. Hornwort will dissolve after about 20 minutes in a medicinal dye. That is more easily replaced than your favorite fish.

What is making the plants look unsightly? That is probably something to deal with after cleaning up the water through progressive partial water changes and treating the Ich. Don't pour an antibiotic into the tank now. It may destroy any beneficial bacteria which are breaking down fish wastes as a part of the nitrogen cycle. The sudden spike of ammonia that may cause, along with the already dirty water and the Ich out break could simply wipe everything out. Well meaning aquarists may kill more fish than the diseases they are trying to treat, if they haven't properly matched the cure with the calamity.

In time, please do mention why the plants need cleaning. Suggestions can be made for helping them after the Ich and finrot are hopefully gone.