Bring the water and beef bouillon cubes to a boil in a large Dutch oven or soup pot. Stir until the bouillon cubes dissolve, and whisk the roux mixture into the boiling water. Reduce heat to a simmer, and mix in the sugar, salt, hot pepper sauce, Cajun seasoning, bay leaves, thyme, stewed tomatoes, and tomato sauce. Simmer the soup over low heat for 1 hour; mix in 2 teaspoons of file gumbo powder at the 45-minute mark.