By specifying those directories you are doing a lot of duplicate backup. Selecting the modules is enough in most cases.
Take a look at the documentation here: Backup and Restore FreePBX 15+ - PBX GUI - Documentation and especially item 4c in the table pertaining to when you might need to specify additional directories. (custom files in /etc/asterisk, call recordings)
Other things - MOH, sounds, configs - are backed up as part of the module selection. To get a full backup, select all the modules.
Backing up the webroot is not of value because to restore FreePBX you have to restore it onto FreePBX, which already has the web files in place.
The most important thing to do is test it out by performing a backup and restoring it on another server. Spinning up a VM or cloud server is trivial and restoring your backup there will show you whether you have all you need.