The tools work because the backup file has a defined, albeit proprietary, structure documented in the tool source code.
The most reliable method involves using the project available on GitHub. open mikrotik backup file repack
This version introduced significantly hardened security. Backups are encrypted using AES-256-CBC with a SHA-256 key derivation function (KDF). Even if you do not set a manual backup password, RouterOS uses an internal system key to protect the integrity of the file. The tools work because the backup file has
If your goal is to have a file you can easily edit and "repack" manually, you should use the method instead of the Backup button. Mastering MikroTik Backups - Free MTCNA Ep.9 open mikrotik backup file repack
INPUT_BACKUP="$1" NEW_IP="$2" OUTPUT_BACKUP="repacked_$(date +%s).backup"