You're up against a bunch of un-clarified stuff.
Erudite has lots of rai/raw negotiating points.
Take the repertoire --- does it work like the
Wizard spellbook / Archivist prayerbook,
so it'd be once in the repertoire = always in the repertoire
or does it have an extra cost like: you know a "spell"(power)
now you make a "scroll"(powerstone) out of it,
then retrain/psyref the known spell, next copy that
old spell from the scroll into you "spellbook"(repertoire) ??
The one is about as powerful and similar to a Wizard,
the other is significantly more expensive than Wizard.
Chameleon Crafting from Dr#349 is yummy cheese ...
Mind's Eye has some acfs for the Erudite.
Magic Mantled version could get lots of PsyWar powers.
The Discipline Erudite variant can do what you're describing
with your Archivist examples 1, 2 and 3. But it can only do it
with One discipline. That is, directly from Divine to Psi.
Archivist bippies* divine things over to a Wizard.
(* bippie is a technical term) I'm not an Archivist guy
so I can't say what alls involved in Div/Arc transfer.
Wizard then is accessible to Spell To Power Erudite.
Yeah, that's how that happens.