To read all comments (by any user) linked to a specific observation the accessing user must have Read observations (3) permission on the feature the observation belongs to.

To create a comment for a specific observation the creating user must have Comment Observations (5) permission on the feature the observation belongs to. Comments can be created regardless of the approval status of an observation.

A user can delete all comments on an observation if he has Manage (7) permission on the feature the observation belongs to.