Thank for the answer and for the links !
I'll soon open an account on GitHub, I think...
Too bad that extensions cannot be cleanly internationalized : I'm french and this extension concerns really a large international public, quite limited, sure, but *really* international (American, English, Spanish, Portuguese, germane, Japanese, Chinese, Vietnamese,Russian, is a minimum)...
So I'll probably have to distribute patched versions of various inkscape.po files, at least for french which I made for me and works quite well, but I don't like this idea too much...
I will still think about that and see what I can do with the international origami folders to build up the corresponding po files both for Inkscape and the extension.
Regards,
F.