The consistency of custard or pudding will be stiffer and the baking time may be shorter with less sugar. Reduced salt may affect flavor. It also gives a rich flavor. Sugar lowers the freezing point and lengthens the freezing time so ice cream will be softer at a given temperature. It also helps in the formation of smooth texture and adds sweetness.
Salt adds flavor.
The flavor may also be less sweet and the freezing time may be shortened if less sugar is used. Reducing salt has little effect on flavor. Rof certain microorganisms which produce acid. Acid prevents spoilage. There may be spoilage and changes in texture.