Spells in general seem a little sketchy here - although Spells in the Spellbook are just a bunch of “Effects” (which are recorded upon creation and remain unchanged even if the original Power is modified, or repealed), there’s still a line saying that “A Spell consists of one or more Powers”. Which mans that the four add-one-level Spells in the Spellbook are not Spells, because they do not consist of any currently recognised Powers.

I would argue that “The available Powers are listed as subrules to “Powers”.” does not mean that the listed Powers are the only Powers, merely the only available ones. Previous powers can’t be used in Crafting, but I don’t think those spells are voided.