Heat corn oil in a skillet over medium heat; cook and stir onion and celery until lightly browned, about 5 minutes. Add carrots, minced pineapple, rice, raisins, parsley, savory, and paprika to onion mixture; cook and stir until stuffing is heated through, 5 to 10 minutes. Season stuffing with lemon juice, salt, and pepper. Remove skillet from heat and allow stuffing to cool.
Preheat oven to 375 degrees F (190 degrees C). Grease a roasting pan.
Stand the crown roast in the prepared roasting pan and rub vegetable oil over entire roast. Spoon stuffing into the center of the roast. Cover stuffing with a piece of aluminum foil. Wrap each chop bone with foil to prevent charring.
Bake in the preheated oven until pork is cooked through and juices are amber in color, about 2 1/4 hours. An instant-read thermometer inserted into the center should read 145 degrees F (63 degrees C).
Transfer roast to a serving platter and tent a piece of aluminum foil over roast to keep warm, reserving juices in the roasting pan.
Pour the juices in the roasting pan into a skillet and heat over medium heat; cook and stir pineapple slices until golden brown, about 4 minutes per side. Slit 1 side of each pineapple slice and arrange in a curling twist around the roast.
Carefully skim the fat from the roasting pan juices and add reserved pineapple juice to the skillet. Crumble the bouillon cube into the liquid; bring to a boil. Cook and stir pineapple juice mixture until browned and slightly reduced, about 5 minutes. Transfer to a sauceboat or small bowl to serve alongside roast.
Remove foil from the tips of the pork chops and replace with paper frills. Garnish each pineapple twist with a watercress sprig.