Preheat the oven to 375 degrees F. Presoak 12 bamboo skewers in water for 30 minutes.
For the glaze: Combine the butter, pineapple juice, rum, sugar, tomato paste and vinegar in a small saucepan and simmer until reduced and the glaze has a texture like maple syrup, 7 to 8 minutes. Season with salt and pepper. Set aside to cool slightly so it thickens up even more.
For the meatballs: Set a small saute pan over high heat. Coat with a little olive oil and saute the garlic and shallots until caramelized, 4 to 5 minutes. Season with some salt and pepper. Set aside to cool.
In a small bowl, combine the breadcrumbs and cream and set aside to soak.
In a large mixing bowl, combine the beef, pork, cooled shallot and garlic mixture, currants, Parmesan, pine nuts and moistened breadcrumbs. Sprinkle with some salt and pepper and mix well. Form into 36 (about 1 1/2-inch) meatballs and thread 3 meatballs per skewer. Set a wire rack over a baking sheet lined with foil and spray with nonstick spray. Arrange the skewers on the rack and bake in the center of the oven until the meatballs are just barely cooked but will hold their shape on the grill, 6 to 7 minutes. Remove from the oven.
Heat a grill to high and wipe down with an oil blotted paper towel to clean and create a nonstick surface. Place the skewers on the grill and char for about 30 seconds per side. Once they are browned, brush with the glaze and cook until the glaze is shiny and lightly coats the meatballs, 30 to 40 seconds more. Serve with any remaining glaze on the side for dipping.