The option to save and load spellbooks could have buttons so you can apply them to every units you control, or all of a specific kind of caster (all with 2N 1D), or all of a certain type (all vampires) to reduce micromanagement...
For me, a "configurable blacklist of "never cast unscripted" spells, used for your whole nation" is to be avoided, because I don't want my 2N mages to cast wine arrow, but I do want my 1N mages to do so. I want my 4N 2E casters to use nature spells, but 2E casters to use earth. A configurable blacklist for the whole nations doesn't let me do that, and is therefore in my opinion, not enough.
The solution I propose, however, doesn't prevent AI fixes. So don't choose one or the other, when you can do both.
