I generally think radical suggestions are a bad idea, but I'm going to make two now. First, non-porn simulation elements such as brewing are, in my opinion, not the way to go with this game. If this was a carefully modeled bartending simulation game from the beginning, it would be different, but that really isn't the case here. It takes time from both the story and the porn, and it would take a lot of work, especially in a rpgmaker game, to truly make it shine. It would be better to drop it now then to keep devoting time to something which is highly likely to be subpar due to lack of effective tools and time.
The second is a creative idea involving the bar. Have you considered making Catherine work from the FRONT of the (remodeled to accommodate) bar once she becomes corrupt enough? The issue with the bar minigame is that realistically the customers can't reach Catherine well across the bar. If you did this, suddenly a lot more options become possible. Chuds can randomly grope her whole body, grab her wrists or hands restraining her temporarily, bang her when she bends over, etc.
With the remodel complete, you could then implement a sort of "combat" system with the remodel. A good model for "combat" ideas is Karryn's Prison, though you wouldn't need to implement all the stuff that's in that game. Basically there would be two separate primary minigames, the bar tending from the back we have now, and a new, more complex frontal version where Catherine has to struggle to complete her orders without getting overwhelmed in multiple ways. Many things would carry over, like pouring drinks, but those actions can be interrupted, and in general there would be more direct interaction by the chuds. This would give the game more variety and stand-out because frontal bar tending is not a thing I've heard of before.
The frontal bar would be a lot of work though. New stats would need to be keep tracked of to control chud actions, Catherine responses, and interruption chance. There would need to be new artwork, and the bar itself would take some thinking about. Maybe sliding doors in the bar, and/or an underground system? Anyways hope you consider something like this.
