Since UserService plugin can add additional properties, which were already built-in in Openfire ("ofuserprop" db table) and loaded by default, the User Properties view (user-properties.jsp) should at least let view the additional properties (read-only).
Can you share what additional properties do you mean?
Additional properties can be everything. The property (name and value) can be set by User Service Plugin. E.g. IRC username, Notes, etc.