Poor kitty! I have had a kitty with chf. She was playing and stopped and starte coughing. But not like a hairball cough. It is a tough one for sure. Back when my kitty had it there was only a few things we could do. And she was only 7 we thought she was too young too. But she had a good life up to that point for sure. My heart is with you and your family. I am curious how they treat it now besides the fluid draining and some of the meds we had to give her. She was a hard hard cat to give meds too and thought I was torturing her. That did not help the situation.
Good luck and keep us posted.