Regarding Laumspur, I don't believe it is a magical plant, it is just a good healing agent and grows everywhere on Magnamund (though I don't think it's everf said it can grow anywhere, so not necessarily in every back garden). Also, I think thinking narratively about what it is doing is also one of the secrets to exactly what players can do with their crafting, etc.
So in the gamebooks (not so much the RPG) raw Laumspur and potions had the same restoration bonus. However, narratively / 'real world' you could assume that one is a 'better' bonus than the other. The raw leaf is providing some quick mitigation that for game flow and story flow is treated the same as the better potion or apothecary bought leaves.
So what are the leaves doing? Perhaps there is a temporary numbing effect or adreniline boost thatis what the EP restoration represents, or the leaves can also gum up bloody wounds if used in a quick bandage. Whereas properly prepared potions and leaf bundles are providing a more long term boosting of the immune system, are concentrated and augmented subtly, etc.
So while there is no difference casually between growing the plant and brewing the plant from a gameplay perspective, for the real world and for crafting purposes the leaves are not enough. There may be some long term heath penalties from using untreated leaves, addictions, the body building tolerance to it. So it's still necessary to introduce some skill and time to produce better quality stuff. So you can still limit the amount of good quality stuff available without compromising the system nor needing to remove the coomon, raw stuff from the game.
For the Bor Rifle example, sometimes the crafting stuff is a case of 'well, your character can do that, but it won't change the mechanical factors. It still takes skill to use the fragile rifle as an effective combat weapon, even with more thigns on it. It's still the same CS score, it's more just the narrative effects you can attempt with it (like knocking someone unconscious, say). And it takes a skilled crafter to create the weapon like that from scratch. And then just treat it like a superior weapon with a +1/2CS melee (with the extra cost that implies(
The other way to go would be to make the weapon system more complex, and so crafting things in to it can have subt;e effects instead of just s CS bonus. So if a spear and a quartstaff have different effects, then a rifle with a bayonet can count as an improvised spear to do X, or with striking surfaces as an improved staff with with Y effect.
For an actual crafting system, I would still keep it nebulous and light so that these sort of real world ideas can be introduced to balance the numbers. So perhaps a non-magical comsumeable item takes 1 days per use to make by 1 skilled crafter. You don't day why it takes a day exactly, though you might have in your mind the actual limit of time in your head in case the speed of plot needs to move faster,. So whether a cake, a laumspur potion, or a travel ration it just takes a day. The reason is as nebulous as other commitments, not getting the raw items right away, needing to leave things to stew, settle etc and not instantly getting back to it, etc. So it gives a base time, but one that is harder to abuse unless the plot demands it.
For more complex items, for the same nebulous reasons, say a base of it takes 1 skilled worker 1 week to create a simple permanent item, 3 skilled workers 3 weeks to create a more complex item, and five skilled workers five weeks to create a powerful non-magical item.
And with all of these that time can be crunched by having a set of equal amount of lesser skilled assistants under them. So three skilled artisans need three assistants each to reduce the time to 1 week, five skilled artisans need five assistants each to reduce the time to 1 week, etc.
So you can account for large scale production undertaken by cities or societies, especially gearing up for a war or for retail, while still having it a massive undertaking for a group likely to include the players.
So a weapon takes a week - for reasons not given, the blacksmith has commitments, loses a day lighting his forge on a monday, has to await materials, has a failure, etc. so a crafted item takes a week but there are plot ways to limit that once in a while to the realistic time iot would take.
A Bor Rifle takes three weeks of time, with three craftsmen co-ordinating. A keg of Boompowder takes five weeks with all these skilled Dwarves co-ordinating. It's an easy set of numbers for gam,e balance, and you can fudge the reasons so its not abused but can be tweaked as needed.
The other way to go might be setting a GC level. So say a skilled tradesman can create 10GC or 20GC worth of produce in a weekm depending upon their skill. Once more, keep exactly why and how loose. So a superior weapon would take 15 weeks to build, if the craftsman was very good, and reduced their output to 10GC a week for 15 weeks. The reason being they take time out of their schedule to visit places to get good material, they make proctise weapons to perfect a technique, etc. It's balanced, it could be circumvented if you need a perfect weapon built quicker, but otherwise it's a useable framework.
That would be the two ways I'd do it, anyway, and I'd certainly lean heavily on hand waving the narrative reasons why it takes that long to ensure that it isn't abused badly and the mechanics don't impose on your story needs.