I don't think I did but that would explain why I can't find it. I have now obtained every entry aside from 16, assuming that the entries go 1-18 then the ???, that I know of. Now I just need to make it snow or otherwise find the desaturated trees. That should then allow me to craft the recipes unlocked by making it rain and letting me find the key to the magic chest.
Is that catalyst the C-Remover? It can't be since it requires a true hydra to craft it. Is the catalyst recipe found in the magic chest or painted chest? Is it related to the second set of numbers you found for the cabin library? How would someone go about painting the chest in the first place? Never mind about the painting I figured it out. Every recipe I currently have written down aside from the C-Remover needs Frost Caps but I'm seeming stuck in a loop of needing to solve the hydras to get to the Frost Caps and needing the Frost Caps to solve the hydras. The Malice cure needs Frost Caps. The walk through matter potion needs Frost Caps. The only recipe I can actually get the resources to craft that could possibly be called a catalyst would be the suppressant but I don't think that's it.