I'll try to keep this serious, but a smile is on my face as I write it.
I don't know how much experience you have of dogs, especially Collies and
their varieties. I've kept Border Collies for over 30 years (currently on my
fourth), and in that time I reckon I've got to know them pretty well.
Basically, a Collie couldn't care a damn what you call it. It will respond
to it's master's (or probably in your case, it's mistress's) voice without
hesitation. Mine, well she responds to anything I call her, most of which
names you'll never find in a reputable dictionary. :-) If you keep more than
one dog, then a name does become important, and you have to teach the dog to
respond to that name, and no other. But a dog on its own will take notice of
its owner everytime they speak, whether to the dog or to someone else. I
live on my own with the current lodger, and you have to see what's happening
here when I'm on the phone!!! (Same thing applied to previous lodger, too.)
So my advice is for you to choose a name that you (& SHMBO) are happy with.
From the word go, alternate between Bouncer and the name you choose, and
within a few days she will have accepted the new name, and within a week
will probably have completely forgotten the old one.
jim