The roads I take...

I've been working on this for a few days now - and with some teak of last night it finally started working:

Localized nightlies for SeaMonkey "trunk" (i.e. those from latest-comm-central-trunk-l10n) now get automated updates, just like the US English ones do!

Of course, you'll only get an update if one is available, but string changes in Mozilla or SeaMonkey areas should not pose problems, our build system "merges" localizations for nightlies with the US English strings, so that you just will see untranslated strings where the localizer still has work to do.

In case ChatZilla or venkman have missing strings, we will break in the build stage and not produce nightlies or updates, though, as the "l10n-merge" process is currently unable to deal with those extensions.

I hope nightly testers will be happy and our localizations will get even more testing even before we ship alphas, betas or releases!