I want more liquid reactions. A+B=C type of reactions. For example, MERC reactions with METL like mercury reacts with aluminum, corroding the METL and replacing some of it with MERC. Or RSST reacting with OIL and making WATR or something. Stuff like that really increases the amount of cool stuff you can build in-game.
Your desire is noted. However, your example of merc+metl corrosion is never going to happen, as merc is used with metl in many rng switches and heat switches.
RSST+OIL making WATR... why would this be useful or helpful or fun? Do you just want reactions for the sake of reactions, without a care for how or why or what reactions are actually implemented?