10 Favors for the spell learning action is actually pretty reasonable when we break it down.
We currently have four spells we want to learn, ignoring Shadow of Death since it's redundant.
Learning them would take at least three actions - one for Invisibility, one for the two partials, and one dedicated action for Cloak Intent, since at that point taking the gacha would be a coinflip between a useful spell and a useless one.
Those three actions would cost two Favor on their own, so combining it all into one action basically costs us 4 Favor per action saved, with the added benefit of giving us the College's higher baseline bonus to learning the Partially Complete spells.
4 College Favor is basically the amount we get from Serenity each turn, so turning it into an AP is basically trading the Serenity writing action for an actual action - a trade I'd take any day.