It is rare, but they will host...obviously. It is pretty cool when it happens. Can you take a picture for us? And as for the glass anemone shrimp, they cover themselves with mucus from the anemone so they don't get consumed...they have to hide when they molt and re-coat themselves.
BUT, as for the original question at hand, I wouldn't add any other fish. One of your clowns will most likely be bullied to death when they can't find enough space to have their own territory in the tank.
I'm also concerned about those mandarins. They are hard to care for with their pod diets. I spent a ton of cash each month pouring pods
into my tank to keep one alive. Even then it only lasted over a year before passing away.
The good thing is that a 65 is a great tank. Returning a clown and mandarins would open up the possibility of other neat fish, like a firefish or a small wrasse.