Wow, I can't believe that people are still playing this. Thanks a whole lot for your support, especially Chalicier. I've gone ahead and incorporated his fixes into the OP and will continue to do so with any new ones for the foreseeable future.
Right, I've tracked down the Raw Prometheum problem.
In short, it wasn't "not being called clay" as I suggested a page or two ago. Instead, the problem is that Raw Prometheum has two occurrence tags - "SOIL_SEA" and "CLUSTER_SMALL". Turns out that clay collection zones only recognise soil-types as being valid, and so the small inland clusters of Raw Prometheum cannot be collected, and getting it from the shoreline is... difficult.
I'm going to fix this by leaving the shoreline Prometheum as it is (we can assume that the oceanic deposits remain relatively raw) and add a new CLUSTER_SMALL type which can be mined. I may call it "Isomeric Prometheum" and add in a (possibly expensive) reaction to turn it into Raw Prometheum.
I'll link up another version of my raws when I'm done. This version will also have my fixes to schematics (there's a few typos in the reagents for schematic-dependent reactions) and, if I can figure out where the problem is, sheet metal rollers. I'm also hoping I can make sheet metal do some more interesting things than "being in cogitators".
I just wish there was some way to make projectiles disappear after firing so we could have Las weapons. That would be a wonderful use for all those crystals.
edit: Just to be clear, I am not offering to take over development of this mod. I'm currently quite ill and spending a lot of my time playing DF and in particular this mod (and thus fixing the problems I'm encountering as I play), but I'm mainly concentrating on my own roguelike based on the tabletop RPG Exalted. I will however keep uploading my fixes as I make them - I consider it a form of thanks to the original developers for making this mod in the first place.
I thought that having it as an inaccessible soil layer and a cluster at the same time might trick the clusters into yielding clay without filling up entire layers with it. It's a shame that didn't work, because I originally intended Prometheum to be a renewable source of fuel accessible only with advanced technological infrastructure. The fact that cogitators still use sheet metal is an oversight. I meant to discontinue that when I took over the mod. Earlier, I intended for the player to be able to stamp receivers for autoguns and autopistols, but milling is already efficient enough that the extra effort isn't that worth it, especially when all the other components have to be milled/hand-forged anyway.
Gonna have another stab at getting all the reactions working properly over the next few days.
I'm also considering adding a Scavenger's Workshop - kind of the opposite of the Reclamation Centre, in that you use it to break apart equipment for components. Something that keeps annoying me is that I can find myself with a half-dozen salvaged metal torches but no power cells - but every one of those metal torches has one in it, trapped So I'll add reactions that have a probability of producing each component used to make the object in the first place. Not everything will be salvageable, of course; I'm thinking things like circuit boards and so on are unlikely to be much use to Hivers as the plastic etc is all shaped permanently to make it.
I liked this idea so much that I went ahead and implemented. You can now most of the stuff you get from sorting scrap and a few things you don't into component parts at the Salvager Workshop. Hopefully it won't be cripplingly bugged.
In the long run, I'd love to be able to make the other cultures playable - particularly Ratskins and Scavvies. They essentially live the same way as Hivers anyway, just with different emphasis - Ratskins on harmonious living and Scavvies on low-tech. Ratskins in particular would be a good excuse to rustle up some fun interactions, although I don't think we'd be able to make them immune to dust storms etc like they should be Redemptionists would be kinda fun, too - SO MANY FLAMERS!
Also, I can't get the idea of a "Tyranid Nest" mod out of my head...
Scavvies would be great. I imagine it would play a lot like Kobold Camp in the Underhive, except with the ability to put your useless immigrants to work as delicious scavvy burgers. I don't know how well zombie herding would work - I played a whole lot of mean tricks to get them to appear together with Scavvies in dorfamunda, and even so they often decide not to fraternize with dead people. Castes might work, but the idea of a female scavvy giving birth to a zombie baby makes my brain hurt. Redemptionists might not work in an adequate manner since the flamers exist only through caste trickery; I suppose you could fiddle with morphing gas but imo there's not enough things different about them that you could implement in the game.
hmm.. nid nest. maybe you could add in 'stealers then? make them a seperate caste in each civ that doesn't occur naturally but can be morphed into through syndromes/interaction?
I don't have much experience with modding creatures and castes, but that.. seems. possible?
and I just LOVE this mod. it just breathes 40k's atmosphere.
I've actually had the raws for Genestealers since A&D were in charge of the mod. The reason they're not in is that they aren't all that fun to go up against, or too much fun, depending on your point of view. And they never get to use their oviposition attack because everyone they attack dies in a few seconds. I think Genestealer subversion could be implemented with a series of interacting interactions but I'd need to figure out some way to make it fun - ie, getting a slow build-up of mutants who evolve as they gather numbers, resulting in having to seal off sections of your fort/prepare through the tactical application of flamethrowers. Having your settlement destroyed instantly when an immigrant shows up and turns into a Genestealer seconds later is no fun in my mind. But, in any case, getting what's already in the game to a playable state should be the priority here.
Again, thank you to everyone for your continued support.