What is the ruling regarding the consumption of sweets and cheeses that may contain suspicious or forbidden ingredients such as gelatin and lecithin, and fats of unverified origin (plant or animal)?

The basic principle regarding foodstuffs is permissibility, unless it is known that they contain something forbidden, in which case their consumption becomes prohibited. As for that which is doubtful, piety dictates leaving it. Accordingly, the basic principle for sweets and cheeses is permissibility, unless it is known that they contain forbidden ingredients such as pork fat or meat from an unslaughtered animal, in which case their purchase and consumption become prohibited.