I am curious as to your reason for thinking that hippocras was “syrupy sweet.” Le Menagier’s recipe has quantities for all of the ingredients. When I first made it I found it too sweet and too spiced, so reduced the quantities. Then someone pointed out that, while the sugar and spice are by weight, the wine is a quart by Paris measure. It turned out that the Paris quart at the time was almost two of our quarts, so in getting the concentration to taste I had actually gotten it back to about the original ratio of sugar to wine.
That raises another point worth mentioning–units of quantity. Medieval Islamic recipes, which unlike European recipes quite often give quantities (by weight), use the ratl and uqiya, commonly translated as pound and ounce. But there are twelve uqiya to a ratl, like our troy system, not sixteen, as in the more common modern system.
I also disagree with your suggestion that one should deliberately change quantities to fit modern tastes–for two reasons. The first is that I don’t do that and end up with food people like. The second is that I don’t see the point of cooking from early cookbooks if you are then going to modify the recipe to be more like what moderns are used to.
When my database (The Sifter) is up and running, I would love to work with you on how to coordinate inputting.