small thing I noticed that seemed to be a bit of a bug
to promote a blacksmith to an engineer you need a blacksmith of level 2 and an engineer’s Wrench…
however you need to be level 3 to make the wrench.
the herbalst/ cleric
the potter/masion or the mason/potter ( depending on what faction you choose)
both need level 2 and you can craft the item by that crafter at level 2
not sure if this would need to be adjusted
The idea with cleric is pretty clear: you need a cleric, you get a herbalist, level it up to 2, and convert. The idea with engineer is slightly different: you need an engineer? really? why? ok, you’re probably just out of things to do. here, get a second blacksmith, level him up to 2, and have your 1st lvl.6th blacksmith craft him a wrench.
sorry to poke you @Relyss was this a mistake? 
oh on a side note the new unsable a24 still shows alpha 23 unstable 
i imagine your not supposed to convert your first blacksmith to engineer… rather make a second one to level 2 to upgrade… which is the reason.
well a cleric takes level 2 and the talisman used to promote them ( the book) requires level 2
for RC the mason requires level 2 potter and the item requires a level 2 potter as well, same for TA you need a level 2 mason to both craft the potter chisel and to promote to a potter
to me you should only have to need level 2 to make the item since you can promote at level 2. all the other classes need an external crafter
the difference there is you cant use the engineer without the blacksmith… all the other class promotions are standalone and can take care of their job on their own… the engineer however requires a blacksmith to function… so they expect you to use your second blacksmith to make an engineer… and not your first one.
promote your blacksmith to a engineer then promote someone to a blacksmith that way you still have a blacksmith
that would leave you short on iron bars to make iron cogs with – though there’s a good chance that a well-stocked town could actually get their rookie blacksmith up to ironwork while the new engineer is stuck making bronze cogs at level 1, I reckon @AdriannaVentara is on the right track with that reasoning.
This would be a question for the designers (@Rabid_Llama).
But I think the reason is probably a mix of what has been answered above.
Recently we tried to give the herbalist a little more purpose (now they can craft seeds for placeable plants, and other items after unlocking them), so not sure if / when we’ll be revisiting the blacksmith-engineer connection. 
The promotion level check and the talisman recipe level were probably picked by feel at separate times without cross-referencing, and haven’t been tweaked since it kind of works. As has been mentioned, you kind of need to keep BOTH a high-level Blacksmith and an Engineer at the same time anyway, so it doesn’t super matter what the level reqs are.
More broadly, I want to give the engineer more stuff to do, dial back their reliance on the blacksmith, and possibly even change what they’re a promotion from? I always forget that Blacksmith is a “base level” class and expect it to promote from Mason for some reason. Maybe Mason -> Blacksmith (HAMMER THINGS) and Potter -> Engineer (working with fine details)?
In any event, I haven’t actually done much hard thinking about Engineer yet, but I feel like Engineer and Herbalist are the most in need of love.
I’d actually like to see the Engineer become a separate, base-level class (still unlocked through a high-level blacksmith building the trinket.) My reasoning is this: first off, the engineer works in a different domain to all other crafters, everyone else builds largely “static” designs with few moving parts – a hinge perhaps, or sliding drawers, but nothing like cogs or the presumably more advanced stuff coming in the Engineer’s future. Secondly, it already takes a lot of effort to provide the iron and bronze bars that an engineer will need for their early constructions in order to “train up”, but if the engineer also has to reach a couple of levels in another class first that increased experience cost per level-up makes the task even more difficult. Currently, by the time I have my engineer leveled up to the point they can make traps they’ve already made enough cogs to build all of the traps and turrets they need to fill out their caps, plus a couple of spares, so if I want to train more engineers in order to have more traps/turrets that means a rapidly growing stockpile of gears.
I reckon that starting the engineer as a base class alleviates that problem a bit, and then the mining task can be removed from the engineer’s list of jobs to put emphasis back on it being a building class. The blacksmith might even be able to create the wrench a bit earlier, so there’s a better chance to have an engineer before you’ve hit “late game”. It would make a lot of sense if some of the more advanced tier 3 items (particularly in the Ascendancy’s military path, and the Rayya’s Children path which unlocks all those fancy architectural items like large arched windows) are constructed by the engineer; but for other paths the engineer doesn’t have nearly as much to do… in fact unless the class gets some amazingly powerful machines to build or other abilities, I can see some players doing without it entirely, particularly if they’re building a “self sufficient” town (e.g. Hearth of Cheer where the town is able to provide all its own needs and focus on stability and happiness.)
While the subject of late-game engineer constructions is up, I’d also like to suggest giving the engineer some earlier “experiments” to build – they could be largely decorative or joke items which the engineer is using to test out theories, before using what they’ve learned in “proper” creations later. The turnip shooter is a perfect example – I can imagine that the engineer was inspired by a chunk of food being lobbed across the dining hall by the levering/trebuchet action of a spoon, which prompted the construction of the experimental turnip shooter, and then eventually leads to the “proper” turret. At higher levels the engineer might refine the turret further, building a larger ballista for taking down heavy enemies, or some other improvement on the design. The same might be the case for pumps later on – the first experiment could be a simple fountain which is merely decorative, but later we see powerful pumps to drain lakes or clean up floods. Or even think of something like Newton’s Cradle, the initial design is merely a proof of concept which makes a cool decoration, but later it leads to pendulums which can allow something like clocks (a much nicer decoration and very expensive trade goods.)
I think Engineer as a base-level class (with a kind of hard to get talisman) is a good idea. I might even want to put some wood and stone contraptions in there for them to build early on, and move all of their current stuff to level 5/6
The Engineer is a class in need of a role definition - right now, they’re defense builders, but they could be so much more.
I still like the idea of crafting time revisions so that mechanisation would make sense.
For example, instead of having a cook crafting flour one step at a time a constructed grindstone and windmill or waterwheel would allow five units at a time, or similar. Blacksmith could get a powered hammer, and make higher level metal items require a LOT of hammering which a mechanical hammer could reduce the time of.
This only really works if the economy and game flow can be adjusted to make items take longer to create.
And failing that there’s always room for clockwork single use soldiers that consume valuable materials as an economy sink. Also decorative items (fountains that squirt, mechanical clocks etc) could be included.
Why not also include components for other classes? For example if ever door strenght/secuirty is an important aspect then make heavy duty doors require a lock to go in them. Starting with a wood or stone mechanism, followed by metal. Impressive raise/lower toggled portcullis anyone? And why not add in traps, dwarf fortress style? All of that hinges on the game including enemy types who pose a large threat to the player, so large that the player will consider making a proper small fortress for their town.
Honestly as a player who enjoys town-builder games in general I value interesting looking classes and their crafting animations just as much as their actual gameplay function.
Of course, if we get enemies who move in different ways (climbing or so on), then different kinds of defences to combat each type become important too. And it makes sense for the engineer to be the one who constructs those different defence types (as items, like how fences work); although some of them could have early-game options which are less effective… e.g. a wooden pallisade wall might stop climbing enemies, but is vulnerable to enemies who break down defences; the late-game option might be a wall with concealed spikes which stick out when something tries to either climb over or bash through it.
It’s unfortunate you guys said you’re not going to do much with water right now. It would be a perfect occupation for the engineer, to build levees and canals and whatnot for irrigation or industrial purposes, waterwheels and so forth. That said, I think I would most enjoy doing those things when I can build around them effectively, for which we do need the new building editor.