Are the effects of high-heat cooking on formation of advanced glycation end-products (AGEs) an important contribution or minor compared to subsequent AGE formation in the body following food ingestion?

There are excess effects of improper cooking for some individuals who have an unfortunately more dangerous style of doing things. But as a general rule, most people will not be happy with a completely raw diet and will need to live with some ongoing risk that is unavoidable to have the benefits of a hot meal. On average, cooking is less important in creation of AGEs than what will happen from those same foodstuffs being ingested and then catalyzing glycation within the body. So it is something to be aware of, but the greatest benefit in avoiding this hazard would come from moderating carbohydrate content of the diet to begin with, cooked or uncooked.