Custom roles allows to group a custom set of permissions and grant them to the users and groups. Custom roles are project roles. Like the built-in project roles:
Custom roles are defined at the workspace level.
Custom roles can be granted at both the workspace level (meaning all projects) and the project level.
To create custom roles, go to IAM & Admin > Custom Roles. Click Add role to create a new role.You can choose Import from role to build your custom role based on the existing role.
If you want a role to approve and comment the issue. You can create a Project Approver custom role
based on the existing Project Releaser.