Yesterday we changed the way that you create localized builds on mozilla-central.
This works for developers doing regular builds, as well as developers or localizers without a compile environment. Sadly, users of artifact builds are not supported.
For language packs, a mere
./mach build langpack-de
will work. If you'd rather wish to build a localized package, you'll want to get the package first. If you're building yourself, that's
./mach package
and if you want to get a Nightly build from archive.mozilla.org, just
./mach build wget-en-US
If you want to do that for Firefox for Android, you'll need to specify which platform you want. Set EN_US_BINARY_URL to the latest-mozilla-central-* path for the binary you want to test.
And then you just
./mach build installers-fr
That'll take care about getting the french l10n repository, and do all the necessary things to get you a nice little installer/package in dist. Pick your favorite language from our repositories. Care for a RTL build? ./mach installers-fa will get you a Persian one ;-) .
As with other repositories we clone into ~/.mozbuild, you'll want to update those every now and then. They're in l10n-central/*, a repository for each language you tried.
Documentation is on firefox-source-docs.rtd, bugs go here. This works for Firefox, Firefox for Android, and Thunderbird.
And now you can safely forget all the things you never wanted to know about localized builds.