If I were to guess the biggest problem is modified fats and high temperature processing are the biggest dangers

So no, lab grown meat wouldn't have that problem provided they don't use modified fats or steam canning you should be fine.

The thing is whatever trace contaminants are in the substrate will manifest in concentration in the meat

Can you think of anything more processed than trying to grow meat in a vat? I can't imagine what chemicals get pumped into that to make it grow.