Everybody should be able to recover a database with just reading clear documentation. That documentation has to be written, telling about the recover process, and in general, the internals of how backups for databases work. Because database backups refactoring is still a work in progress, we need to wait to have it almost feature-complete. Once it is, we should have both end-user documentation for general operations, as well as for developers of tooling.
Documentation most likely should be on Wikitech wiki.
So far this is what we have: https://wikitech.wikimedia.org/wiki/MariaDB/Backups#Recovering_a_logical_backup
Code also should be reviewed to be better documented and self-evident for other potential hackers.