Thanks for the reply,
Firstly, po-mode.el has a
bunch of portability hacks, which cause several warnings when compiled
with the latest Emacs. If we put it on GNU ELPA, we might need to
adjust them, perhaps breaking compatibility with older Emacs (though
personally I tend to agree with that).
Compatibility hacks are not uncommon for emacs packages, but I can say I compiled it as a package on the latest development branch without any problems recently. So I don't see a big issue there even if there are a few warnings as long as it works correctly with the hacks.
the authors would need to assign copyright for Emacs, as well as for gettext.
This is true, but if getting authors to assign copyright is a problem there are other ELPA repositories besides the official GNU one,
Melpa being the most popular. As long as po-mode is licensed for distribution outside official gettext channels, getting it on Melpa would be very simple. Though I do think GNU ELPA would be most appropriate.
I will write to emacs-devel, and get their thoughts.
Thanks