I did it once with a faux leather jacket. The sleeves where extra-long (I've never seen such long sleeves, like not even on male clothes) and the main problem was that there was a little zipper at the end of the sleeves.
It was impossible for my seamstress to save the zipper detail, but she managed to shorten them leaving a very nice little slit where the zipper was.
It can be very expensive (I paid only 15euros because my seamstress wasn't sure she was able to do that properly and slightly messed up a sewing, but really it's unnoticeable), expecially with real leather and when zippers/studs/decor are involved, ask a tailor how much will it cost and see if you like the jacket enough to pay for the alteration.
PS: some cobblers can alter leather jackets too. They not only fix broken zippers and studs but also do minor alterations such as shortening the sleeves, at least in Italy where I live.