The sleeves on the FJ can definitely be shortened. I didn't shorten mine because when I wear a jacket or a heavy knit underneath the sleeves are pulled up to the perfect length. When I'm not layering heavily then I turn back the cuffs.
I should add that my fall/winter FJ is 48S but my spring/summer one is 46S since there's no need to layer. The sleeve length on the S/S FJ is perfect for me.