A lot of these production decisions don't really make sense.
Like, apiculture produces either wax or honey?
Honeycomb contains both.
Animal husbandry produces either meat or fat?
Cows contain both.
I get that it's about balance, but it's a little weird.
Also, I'd hope it's eventually possible to respec provinces if your production is all kinds of fucked.
Yeah, I understand what you mean. And indeed, I have pondered about this a lot myself.
The problem really is more on the technical side here, as there is a great disparity between the different animals.
In the early planning stages of the mod, animals would each produce two animalproducts, which made more sense for Apiculture especially, as you pointed out.
However, there were a few problems with it because
a) it bloated the province interface even more, especially with two animals in a province - and while you might be using ARKOpack to mitigate this issue, I can tell you my plans require a LOT more province modifiers for various other things in the future (did anyone of you ever open up my modifier_icons.dds file?

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b) it brought problems with Sericulture - because Sericulture can only produce one thing, it would use only one animalproduct slot. And for the technical framework, it is very important to me that I can assume uniformity between the various tradegoods lest things get much more difficult.
c) it was still only a compromise - "Flock" (Sheep) for example can produce RawMeat/AnimalFat/Milk/Wool/Hide, and by only producing 2 out of them it would still be strange - why can't I eat the sheep if they give me wool and milk? And if I would allow an infinite number, I would just aggravate a) and b).
So in the end, I decided it was to be capped at 1 animalproduct for mainly technical reasons.
I think it represents more of a focus; are the local cattle breeds for milking or for slaughter? Is the infrastructure in place for large scale tanning or is the preparation of meat or tallow the main industry?
And this is the explanation in lore ^^
Seriously, this is a very good explanation - otherwise you would also have to find it weird that some provinces do not produce grain at all, even thought that was such a staple food it was basically produced throughout the entire world, and in almost every province.
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Tradegoods in this mod should only represent those goods that were produced in quantities greater than the local need for subsistence.
So if you want, you can picture the local population eats up all the honey, and thus can only export the wax
That said, it's be nice if you could somehow link different industries relating to the same sources for bonuses (e.g. cattle into meat and cattle into leather in the same province gives more profit than the sum of the two individual bonuses, likewise wool into cloth into clothes gives more bonuses for cloth and clothes than the individual industries alone) to represent the bonuses of reduced infrastructure cost for keeping the whole production chain local.
That is an interesting idea, however, I am not sure how to represent that since province modifiers are not very dynamic.
Basically, I am building a trade framework onto something that was not really designed for it, and it's not easy to dynamically account for anything like that except with additional events and province modifiers, which in total would lead to the problem I mentioned above as a).
Furthermore, I am not entirely sure it would mirror historical reality. Let's take your example and look at the (quite famous) English wool trade:
Wool from sheep in England was exported to continental Europe, a trade so important because it generated revenue for the English king, and so lucrative that the right to collect the tariffs on wool was given by the king to moneylenders as a payment of his debts.
The wool could then have been imported into Flanders, where it was spun to great quality cloth that was sought-after in all of Europe - which in turn made the entire region insanely rich.
However, that cloth would not necessarily already be tailored into clothing - maybe it was imported to say, Paris, where the local tailors produced a pretty clothing after the latest fashion there.
All in all, the products have been traded over large distances, but it generated wealth for many participants along the way, because the final product is much more valuable than a rough wool cloth tailored directly in England. It's almost like "globalization" (which is under a lot of fire in recent years) already existed in the Middle Ages ^^
Now, I am aware that this does not work for everything - e.g. it is nonsense to transport sheep from England to Venice to have them slaughtered there, and the raw meat to Lübeck to have it salted. But to avoid such silliness, the tradegoods have traderanges which restrict the logical distance they should be traded.
TL;DR probably not going to happen, sry ^^