I would keep throw blankets across the back of the couches just in case. Our kitties love to walk across the back of our couches, or sleep on the backs of our couches. I can see how if they were to jump off, it could leave a mark, depending upon the leather. Cats are usually gentle creatures, so even if you clip her claws (which you should do), unless it's really fragile leather it shouldn't
be a problem.
But we use the throw blankets because it's easier to wash them every week rather than vacuum the couch - but that's for us non-leather folks.
(They're also easy to fold up and tuck away when visitors arrive
With plenty of scratching alternatives, there shouldn't be a problem. Also bear in mind that kitties love to stretch and scratch (scratching is often part of stretching) when they wake up. So placing scratching mats, posts, pads, whatever, near where kitty takes to napping will also help.
I really hope you adopt that doll - and if you have any other questions, TCS is here!