Given that they'll easily reach more than 1 mbyte each, translations should be packaged separately, one package per language, so that they can be installed by site maintainers. It also streamlines delivery of new translations.

The files should be extracted from the repository connected to crowdin.com (ezplatform-i18n), and made available using packagist.

Important: installing a translation should NOT require enabling a new bundle in the kernel. Options should be investigated in that direction, for instance using a custom composer installer/package type.

QA testing :

Translation other than english are store in dedicated packages in https://github.com/ezplatform-i18n.
So if you want to add a language you just have to add it with composer (commands are located in each readme files) and clear cache.

You can see the translations progression on crowdin : https://crowdin.com/project/ezplatform