As a disclaimer, I'll say that I have never processed raw tobacco before nor made my own casing, but I have researched it in preparation to do so. That said, based on my research, my understanding of the use of the vinegar is as an acid to aid in the chemical reaction necessary to invert the sugar used in the casing from sucrose to glucose + fructose, which creates "invert sugar."
This invert sugar apparently bonds better to the tobacco (it does not crystallize) and is also highly fermentable, which I assume aids in the aging process. Invert sugar is also more hygroscopic, so it would naturally help retain moisture better in the cased tobacco (in baking this keeps your baked goods more moist).
It's talked about in this video on casing tobacco (though he admits he doesn't fully understand the science behind it):
In researching invert sugar, I found a recipe on a distillery blog that claims invert sugar is "highly fermentable" (they use citric acid or cream of tartar as their acid instead of vinegar):
How To Make Invert Sugar (Distiller's Guide) - https://diydistilling.com/how-to-make-invert-sugar/
Having said all of that, you mention that you use honey as your sweetener, which I believe is basically already made of invert sugar, so I would imagine you already receive these benefits.