I might look into using smaller text to display the added Modifier effects. Combined with the limit of 4 modifier slots and the explanation of each modifier being included in the process of making the mix, descriptions should be feasible.
Catalysts will use the existing Catalytic Formula status effect, so the main element that will deal damage is the Trigger.
A Split Strike potion would be fantastic for Burn and Block Buster effects, and would be powerful if you have a lot of Attack to outpace the enemy Defense (so Water might see some use too, or Earth if you stack Stone's Throw).