90% of the licorice imported into the US Is used to case tobacco. I have read where it is done at a level that you can't really discern any taste from it but for some reason, it somewhat harmonizes the flavor. It is in all cigarettes. I am not sure about pipe tobacco, but I assume that it is. Maybe Jeremy or someone could answer that one. I would assume that most of the rest of the average casing ingredient is sugar water in some form whether cane sugar, molasses etc. and then with some blends the addition of PG as a moisture retainer and with some if not most burley blends adding cocoa powder to some degree and not being classified as aromatics. Again, I am going off what I have read on the interwebs.
As for toppings, I know some traditional old timey blends that I won't name out of respect, use artificial plum flavoring vs. real plums, but people rave about the stuff so in that case ignorance is bliss. Most of these flavorings are inert anyway. I have relatives that work in the food flavoring industry and even the "fake" flavorings are usually synthesized from real ingredients.
I would probably care much more about the pesticides that are banned in the US/Canada and the EU being doused onto tobacco in certain growing regions more than topping components in terms of health risk. Also, the fact that I am inhaling hot smoke into my face.......
I would probably like to put a list together of the least cased and un-topped blends as I generally like the "plain" flavor of natural tobacco. For me, currently, whether I am assuming incorrectly or not these are MacBaren Pure Virginia which apparently still has flavor in the casing, HH Burley Flake, GLP Union Square, KBV Van Gogh and other similar "plain" blends.
As for Latakia, it is a mystery to all of us whether they are burning oak, willow trees or used tractor tires, but ignorance is bliss I suppose.