It seems like a lot of the later arguments in that previous thread you linked were in regards to the spread of technology, so I would like to offer a partial solution to that in order to possibly avoid such arguments, focusing on how a single fortress would come across that technology and possibly lose it. Keep in mind, it ignores how having technology would affect your fortress / civilization (e.g. being targeted down for attacks), the reason for doing so (maybe you would have to command it, like how you create work orders and designate buildings?), and any external barriers to or catalysts for a specific method of technological acquirement or a specific technology branch (e.g. hostile dominant culture, personal or racial ethics, invaders, language, physical or mental limitations of being or race, royal decree, etc).
Advance TL;DR: The way I see it, there are 3 ways to gain access to technology, if you were to base it on an actual tech-tree: basic / applied research, books / relics, and apprenticeship. They basically vary on an abstract level by balancing what you have to start with, versus the amount of time and resources required to gain the knowledge, as well as the risk / severity of danger in experimenting with the unknown. The way to lose technology is by a loss of citizens that know about it and objects that could teach it, leaving you with the more difficult method until you can regain the pre-requisites for the other methods.
WARNING: INCOMING +WALL OF TEXT+
One way to pick up technology is through basic or applied research, where a sentient creature is actively combining different things in different ways and doing different things to them, usually wasting those resources in the process, but occasionally figuring out something. This could be as simple as dropping rocks and metals into lava in order to see which are magma-proof and which aren't (for those who would rather figure things out for their selves rather than looking online), or as complicated as trying out different patterns or creation methods for armor. Knowledge imparted would be giving directly to the researcher, and it would be up to that researcher to either write down notes, put together a full book on the subject, or teach it to someone else through use in order to actually "spread" the technology (unless you like your researchers to be supreme beings of all knowledge, surrounded by hoards of item haulers and farmers).
-The limitations of this method are the raw resources and time you have to work with, the current level of technology available to your researcher, and the ingenuity of the researcher. You also cannot learn the base technology of any type of "magic" this way, since your research is limited to the physical realm until you break that initial barrier. I would suppose that research into "magic" fields would also have its own set of negative consequences as well (a pyromancer accidentally self-combusting? maybe a conjurer creating a portal to the circus?).
-The benefits are that it can be done with no outside help. It also provides an automatic boost to the skill level of the researcher once the technology is researched, if it's one based on applied science and associated with a skill (e.g. finding a more time- and fuel-efficient smeltery through theory and focused experimentation would provide a small boost to architecture and smeltery skills of that researcher), in addition to unlocking that technology.
A second way is to learn something from a book or relic. I guess that books could be written by anyone with the knowledge and literacy, but relics would have to be imbued with some way to impart magic to the user. As for using them, each would require a specific tech-tree requirement (can't research carpentry without something sharp), with optional technological advances helping (for instance, yes, a massive porcelain kiln would require armies of woodcutters for fuel, unless you had access to a seasoned pyromancer who could provide sustained heat).
Also, as was mentioned before in the other thread, just using the book or relic won't magically impart the knowledge (unless mental abnormalities get added in and you happen to have a savant doing the learning). For normal beings, just understanding that knowledge of the object would be a skill in itself, based on the quality and technical level of the writing in the book. A technical book would take longer to read, but lend a greater chance of understanding, whereas an overview would be a quick read but not give much of a chance of knowledge in return for the effort. As for relics, the level of technicality of writing could be replaced by specificity, targeting a more specific group of creatures (based on random number created with each being during that being's creation) in exchange for a higher chance of success and lower chance of a "mishap", and vice versa.
After finally picking up enough knowledge for the skill, item, ability, or building, AND attempting it enough times, the unit may finally begin to create the items, use the abilities, make the buildings, or be a dabbling [skill] user. If this is not done in time, the knowledge might be lost do to skill-rust and have to be re-learned.
-The limitations here are the actual objects you have to find/buy/collect, in order to build up that library. These things can also be stolen or destroyed. It's also unsafe, especially with relics, and can have disastrous consequences. Also, the creator of the object could also be sabotaging the knowledge as well (like Leonardo with many of his war machines
-link-), or by outright trapping it and spreading these to the enemy (e.g. books depicting reactions as harmless that would actually kill / maim the user, relics allowing possession of the user or cursing them).
-The benefits are that these consequences come with less of a chance and less severity than researching. There is also a decrease in time and resources required over researching.
The final way is to pick it up from observation, like watching someone else do it. Think of this as like an apprenticeship. With the current military training structure in place, this shouldn't be too difficult to add.
-The limitations here are the teaching ability of the master, the pre-requisite knowledge already having been learned and mastered by that master, and the time of the master spent in teaching the student.
-A final limitation for all three of these methods is the learning ability of the researcher or student. I didn't bother putting it down with any, since it affects all more or less equally.