How to update a language
A language is downloaded automatically every time the configuration is saved and the language hasn't been downloaded already. The tricky part is that Mautic won't download a language if it has been already downloaded. So to update a language:
Open the Mautic file system via SFTP or SSH.
In the Mautic root folder you should see the folder called translations. Open it.
In the translations folder are the languages stored. Remove the folder of the language you want to update.
Go go Mautic configuration and save it with the language you've deleted.
The language should be downloaded again with the latest translations. The translations are generated from Transifex once a day.
If you have any questions about translations, join the community in the Slack #Translations channel.