The issues with this is the dwarven AI.
If I tell them they need a barrel of water, they say "omg, we have no barrel of water, cancel the job". None of them would be smart enough to walk to a well to fill a barrel with water.
The only workaround is to make a custom "fill barrel with water" reaction in a custom workshop, but reactions don't support using liquids. That can only be done with dfhack. In fact, the handpump in the mod does it.
So... yes, I could make alcohol harder to make, but I would at the very least need dfhack for that.
The second problem is that items can't transform with time (again, at least not without dfhack). So no "aging" of wine or whiskey can be done.
Lastly, I'd have to get rid of the vanilla DF reactions in the still.
I think it's a great idea, DF is just not set up that well for it.
As mentioned, I have no clue if that is possible to implement, but I remember that in older versions (?), there was a mechanic which automatically transformed shaped clay objects through various stages of dryness till they could be fired propperly. The same mechanic could be implement for alcoholic interstage products... I guess?
Yes and no, there was only 1 stage. Wet clay => custom reaction => fired clay.
It should still be there btw.