Bowmanoflight

I like the idea of adding a low fantasy magic system into vintage story, mostly because I think it fits really well with how the game is already laid out. Something akin to thaumcraft where, like OP said, mysticism not magic is desirable. Older versions of thaumcraft were way more about the resource intensive process of manufacturing magic and creating resource chains to make magic feasible. One of the major tenants of VS I think is that every item has a resource chain associated with it, whether it be simple like needing clay for cobblestone blocks or more complex like needing to make it to the bronze age to collect hardwoods for furniture or building. The Mysticism is already present in VS with the rust dimension, temporal stability and the entire main story of the game, utilizing jonas tech and cupronickle/ copper to create magic distilleries or apparatuses to do cool things would be an awesome addition that wouldn't change a lot of how the game functions.