The requester Workflow Request can see comments made by a Reviewer after they have Approved, Declined or Reviewed a request in these locations:
Workflow Request Emails
Workflow Request Emails are sent upon the Reviewer's response, pending these emails are enabled under the Workflow settings (default is always on). When enabled and comments are made as part of the Reviewer's response these will display in the body of the emails the Requester will receive:
Workflow Request Email Admin Configuration
The below is the settings in the Admin > Workflows location for Workflow Template which will dictate that Workflow Email Notifications are sent, and to whom, as part of the Workflow process:
Workflow Request List
For Resource Workflow Requests, the Requester can now click the Request Details icon at any time to keep track of this specific request. The Request Details overlay that opens has a Request Status section that will include any comments that have been made by Reviewers who have responded.
In the Workflow Request List (in your 'Workflow' or 'Approvals' tab), click into the dropdown for the Request and then on Workflow History / Approval History
This will list all the workflow requests for that item (Resource, Record or Survey Response). Comments by each Reviewer, for each request associated with this item will display here to give you a bigger picture of the Workflow History for the item.
Note that comments are not always mandatory on Workflows, as this is an option that can be enabled/disabled, so they may not show for all Requests & Items.
* Please note that some of the terms used above such as Workflows & Approvals are customisable and may appear differently in your platform.