> nightly.mozilla.org is available in just 9 locales.
> I don't see a project for it in Pontoon. How can I localize it for 'eo'?
Sorry, my fault! I was looking at the "Firefox + YOU" part of the page, that usually doesn't get exposed until you type the email. But I had NoScript on so I scrolled down until I saw the list of languages and got the wrong one (I hope it appears at the top one day).