Some disappointing news for Alchemy. My testing so far makes it look like we won't be getting any alchemical components from traders. You can still order the base stones, of course, but vials of quicksilver or vitriol or whatever don't look like they're something you can request from a liaison. Not 100% sure they won't show up on the caravan anyway, but I haven't seen any yet.
I'm going to try one new thing. I'm going to make a new Toy object called a Jar, and have the reactions produce a filled jar instead of a filled flask. This will, at least, prevent your soldiers from walking off with your alchemy supplies. You should also be able to request Jars from the traders, although I have no idea if we'll see the alchemy filled ones show up or not.
EDITED: I'm not quite as worried as I was before. Now that I've broken everything out onto a spreadsheet it seems that the Mithril, Levisium, and Elemental metals will require different alchemical items than the Crystal items. And, except for Void Crystal, those should be pretty easy to get.
Mithril is fine. It's far above even Crucible Steel in effectiveness, so I'm fine with it being expensive and difficult to make.
Levisium isn't too much of a problem. It's mostly just expensive and light anyway, since it tends to make weaker alloys.
The Elemental metals might end up being rebalanced a bit. Glacium was originally pretty common, since it was really just a cheap but limited way to get a steel equivalent from iron. While Frost Crystals will probably stay common, I'm not sure how easy it'll be to actually make Glacium with the new system, so I might get a power boost. The other types were always very powerful and rare, so I imagine the additional alchemical steps won't do all that much to deter them any more then their old scarcity did.
Another option is to add in some plants that can provide some of the more common components. Perhaps the wood of some underground trees could be used, to give you incentive to delve deep. Plus, it'd explain why the dwarves are so much better at alchemy than most of the other races. This doesn't look like it'll be quite as necessary, but still might be a neat idea.