Do the users need to be assigned any permissions for the user to be able to create custom rules?
ver: 9.9 LTS
It depends what kind of custom rules you’re talking about – if you’re talking about template rules – you’ll need to have permissions to administer quality profiles (or a specific quality profile).
If you’re adding coding rules via plugin, then you need to be able to install the plugin on the server itself, and then the permissions to add rules the plugin adds to a quality profile.