We're planning to switch language packs to use the new WebExtensions platform somewhere down this week .
This is a very important change on that enables us to enable the first milestone on the path to the new localization API .
In a longer term, we hope to promote language packs to first tier localization experience which would allow us to look into switching from building 100+ builds, to building a single build and 100+ langpacks.
In the short term, this makes our language packs support L20n, but also makes them safer, easier to maintain, and no longer a blocker to removal of the old addons code.
If you notice any issues with the new code, please, contact L10n Drivers team.