Heat oven to 425°F; grease a rimmed sheet with teaspoon oil. Gently mix pork, mashed beans, cornmeal, egg, onion, cumin, oregano, and meatball salt. Form 24 meatballs; bake 18 to 22 minutes until centers reach 160°F.
Meanwhile, heat sauce oil in a saucepan over medium. Stir in flour and ancho powder 30 seconds. Gradually whisk in broth, tomatoes, and sauce salt; simmer 4 minutes until smooth.
Transfer hot sauce and meatballs to a 4-quart slow cooker. Cover; cook on HIGH 2 hours, gently turning once, until centers reach 165°F.
During final hour, boil rice, rice water, and rice salt. Cover; cook on low 40 to 45 minutes until tender and water absorbed. Rest off heat 10 minutes.
Top meatballs with cheddar; turn off cooker and cover 5 minutes until melted. Avoid stirring cheese into a paste. Divide rice among 6 bowls; add 4 meatballs and sauce to each.