Hi Welcome to Fish Lore

I'm sorry about your ADF's. What treatment are you using?
Fish can't get Chytrid Fungus.
The problem I would worry about is cross contamination.
If you put the moss ball or plants in with the fish then use the same syphon, net or anything from the infected tank in your frog tank you take the risk of infecting the frogs again.
If for some reason you had your hands in a tank that had been exposed to Chytrid then put them in the frog tank you risk contaminating them again.
I don't know what the chances are that the plants picked it up but
personally to avoid any contamination, I think I'd toss the moss ball/plant.
Good luck, I hope your ADF's recover.