Not doing anything is much more cruel then making them a bit annoyed at giving them salt baths that may save them. At this point, if you do nothing then they will eventually die.
Leaving your tank the way it is is not a suitable environment for any of it's inhabitants. They kuhlis will eventually end up being eaten...and the frogs will most likely eventually die.
Again, I must insist/beg if you will, that you do something to help these poor frogs. They are truly suffering.