If the ebuild for xorg-x11-7.1 it's stable now, it's not nesessary to have also the ebuild for app-emulation/emul-linux-x86-xlibs-7.1?
Not unless there is a significant change to the Xlibs, one which 32bit apps would require. So no, not for now. If a specific application has a problem, please re-open (or open a new bug).