[Risolto] Deployment error using capistrano because of permissions on (...)languages/wpml/queue

Background of the issue:
I'm developing a WordPress site with Bedrock, deployed to a staging environment using Capistrano. My deployment fails with a permissions error related to the WPML plugin. I know how to change permissions or make the 'queue' a persistent file/folder, but I'm unsure of its purpose. Additionally, I'm confused about the deployment process and how translations are managed between staging and production, especially when translations are done on the production site and new translations are deployed.

Symptoms:
Deployment fails with the error: 'rm: cannot remove '/var/www/html/releases/[...]/web/app/languages/wpml/queue': Permission denied'. (NB the path to the languages directory is normal for bedrock installations, it's working fine with other WPML projects)

Questions:
What does the 'queue' in WPML do, and how should it be managed during deployment?
How should translations be managed between staging and production to avoid losing them?
What is the primary source for translations between translation files and the database?