$(GETTEXT_PROJECT_POT) is always generated if $(GETTEXT_INPUT_FILES) are newer than it. Having this happen automatically is not useful, since it can break manually edited and version controlled $(GETTEXT_PROJECT_POT).
Currently, there's a $(GETTEXT_PROJECT_PO): $(GETTEXT_POT) rule, but since updates to the workflow now considers, allows and mandates one or multiple *.pot files as the authoritative source for translations, make this a pattern rule rather than only valid for $(GETTEXT_POT).
GETTEXT_INPUT_EXTS takes a whitespace separated list of extensions which are subsequently passed to find -name to locate source files which are meant to be run through xgettext.
The first argument to find, translateme, is not really meant to exist, it's just there to allow adding multiple extensions preceded by -o in a $(foreach) loop.
Try to make the workflow a little more versatile. As of this commit, .pot files are assumed to preexist, save $(GETTEXT_PROJECT_POT), which can be generated from source, and should be committed, too.
A directory with gettext.mk in it, provided it has a locale name, makes the parent directory to a working localedir, which can be used from within the janware source tree, so add it with the all target and remove it with clean.