As partly discussed in following article:
There is no way to sent notification if somebody comments a Digital Catalog Request in DWP or in SmartIT.
These comments are written directly to DWP Catalog per RestAPI and available in DWP Catalog Tenant Database in Table myit-sb:ActivityLog. However there is no OOTB neither Custom way to observe these entries and sent relevant Notification in case some comment is added.
We need some solution to be able to inform Users about new comment on their DWP Catalog Requests