I can say that the fix u tried of updating the path to 5.16 in perl5lib might not work because i believe the perl path is hard coded/concealed in the osx code at many places, especialy in the XCode preferences and such.
the gettext software ( i havent used it much..maybe not at all) i assume u installed it by hand on 5.16. thats the start of the problem :D i think . that was system perl. u should have download a more recent version of perl then and updated the PATH variable to use your new version of perl with gettext.
to fix the issue with gettext, u would , in my opinion , have to remove it or find a way to make sure gettext points to the new version of perl installed by yosemite

yes if u install perlbrew and cpanm u will see how hassle free it will be going forward.