The Campaign Builder's Guild

With the Bardics this would make a lot of sense on a number of levels. Bardic lore can encode and hide (and therefore transmit and reveal to those with the right "keys") a wide variety of knowledge. (There's a great deal of evidence that the Celtic Ollam's did precisely that, both in poetics and the use of the Ogham "alphabet") In a setting with strong element of espionage bardic training could be highly useful both in terms of covert techniques (arcane and mundane) and to provide "access" for agents. Not that Bardic Collegiums would simply be euphemisms for "spy schools" but they would provide excellent pre-training and screening agencies - especially for the families and related interests as you describe.

I would then imagine covert Imperial activities upon it's own citizens (especially at the lowest levels) being conducted to create their own magical operatives as a countermeasure policy and/or Secret Police agency. If you've read Rudyard Kipling's "Kim," (perhaps the first distinctly "spy novel" ever written) a good potential example of how identification, recruitment and training might be carried out can be found. Not to say that all bards would necessarily by Old Family spies nor all sorcerers Imperial operatives, just that these activities could be conducted extensively though those particular channels.

That is  exactly the way I was thinking!!!  Anyone who ever plays a bard in this setting will have quite the Backstory...

BTW, any thoughts on psionics in this setting? In terms of deliberately "triggering" the manifestation of potential powers/abilities I think that psionics lend themselves a little more readily than sorcery in that definite psychological techniques can be identified and developed by any society with a reasonably sophisticated model of the psyche. Given access to various "mind-reading" magics such models would certainly be within the reach of these pre-industrial cultures. . .

I was thinking of psionics as a means for a few smaller countries to comptee with the biggies.

In certain arenas that could do well - especially in espionage - developing techniques which magic using nations have little or no counter for. More direct military use I don't think would work as well. I haven't thoroughly checked out psionic powers but my impression is that while they can dish out a lot of damage one-on-one at pretty low levels compared to magic, they have much less punch in terms of area of effect that would be useful on the battlefield. That still fits pretty well in the sense of little guys having to rely on subtlety instead of brute force. One thing that would have to be determined early on is how different they are from magic. In my setting I've been using the different form of magic variant, psionics and magic can effect each other, but at reduced levels. Here treating the two as entirely different would give an edge to psionicists who develop their techniques covertly, including specifically anti-magic powers, so long is they can maintain their edge in an escalating powers race.