Automate update columns in a view with trigger function in plpgsql
I was able to solve my problem in a more manual way. It took some time to complete for all columns but at least it is done. Heres an example, of what I did.

-- update col_d
        IF (NEW.col_d != OLD.col_d) THEN
          UPDATE poi
          SET col_d = NEW.col_d
          WHERE poi_id = NEW.poi_id;
          RAISE NOTICE 'col_d was % , changed to %',OLD.col_d,NEW.col_d;
        END IF;
-- in case col_d is NULL
        IF OLD.col_d IS NULL AND NEW.col_d IS NOT NULL THEN
          UPDATE poi
          SET col_d = NEW.col_d
          WHERE poi_id = NEW.poi_id;
          RAISE NOTICE 'col_d updated NULL to %', NEW.col_d;
        END IF;