You mention prawn malaikari here, which indeed is one of the Bengali classics that skews sweet. The Bengali cookbook I use as a reference (The Bengal Cookbook by Minakshie Dasgupta) has a recipe for this where 1 teaspoon of sugar is included for a curry which includes 500 grams of prawns, 4 onions and 2 cups of coconut milk. I never add the sugar as the natural sweetness of onions, coconut milk and prawns is enough for me. Also, the spice used here is garam masala, which despite being warming also has a sweet profile. Apparently the ‘malai’ in the name doesn’t refer to the creaminess but to the origins of the recipe (adopted in Bengal from Malay traders).
Another Bengali classic with a sweet flavour profile is chholar dal - a thick dal made of split yellow gram, which can include raisins, fresh coconut diced small and upto 4 teaspoons of sugar for 250 grams of lentils.
Bengali cooking doesn’t really have much of a following outside of Bengalis. The flavours are quite different to what is considered ‘Indian’. It’s an outlier!
