Well, there is an obvious way to circumvent this problem by just giving them "Gifted" Major Magical Quality, allowing them to retain the knowledge of Hermetic Arts. Whether or not they'd actually have it is up to the SG but it's not hard to argue that the ghosts of the Founder's caliber would retain their Gifts post-mortem (or some portion of it?).
So far I haven't made a character questing for Caanite Necromancy but yes, this would have so much story potential, beyond simply find it.
On the side note, ; there is a variant of Caanite Necromancy called Pictish Necromancy, for those playing on the British Isles.
What was House Diedne like, and why was it destroyed (we can contact Diedne the Founder, and got names of at least 2 Diedne Primi at different time periods). What happened to Tytalus, Pralix and Bonisagus? Who was behind the Sundering? What are the Tremeres planning? They specifically burn the corpses of their dead so that necromancers can't learn their secrets, which is no protection against a Caanite Magus.
In retrospect it also makes it very easy to learn lost languages and learn more about Hedge Magics (since a lot of hedgies gain their power through initiations, they'd retain them after death).
Either way, it makes for a treasure trove of info.