Together with Thunderbird 38, we will be releasing Lightning 4.0. Both of these releases are not beta versions, but similarly major releases like Lightning 3.3, Lightning 2.6 and their respective Thunderbird counterparts.
We have about 11 weeks left until the release will be final, and while the developers are doing their best to make sure features are stable and there are no regressions, its time to do some translation work.
If you have been missing your language in Lighting in the past, maybe this is a good time to contact the l10n team of your language and express interest to translate Lightning. While the initial hurdle may be large, there are usually not many changes in strings between Lightning releases. If you are lucky, someone had already translated part of Lightning in the past and all you have to do is update your locales. The translation process is fairly simple and can be done using your favorite browser.
If you are already part of the Localization teams, this is the time to head over to mozilla.locamotion.org and translate the remaining Lightning strings. Once you are done translating and the changes have been pushed to the localization repositories, please head over to the Thunderbird l10n dashboard (not the Calendar Dashboard) and sign-off the latest change. Make sure you are signing off the later changeset of Thunderbird and Lightning, as only the newest sign-off will be used.
Should you have any questions, please feel free to send me an email or comment on this post and I will get back to you as soon as possible.