There are certain flavor components of foods that are more or less soluble in various liquids. It turns out that some of the flavor components of tomatoes are, indeed, soluble in alcohol. That is the genesis of recipes that add a small amount of vodka to tomato sauce. Vodka is flavorless, the alcohol evaporates, and you are left with a more intense sauce. I suspect that is what you are experiencing, though you may enjoy the added flavor that the scotch contributes. I don't think that soaking the tomatoes will increase the intensity. In fact, you might lose these soluble flavor components to the alcohol. In other words, you will make tomato flavored scotch. Perhaps not what you want, and these tomato flavors may get lost in the already strong flavors present in scotch. But, I could see value in tomato flavored vodka, for example. For your recipe, I would maintain your current practice of adding the alcohol to the dish as you prepare it.