Pretty sure that meant the scroll they stole was of old plans, which were later revised due to theft.
Invisibility is one slot per person, and only lasts like a few minutes per person, it’s not combat where after a few 6-second intervals all your opposition is dead. Unseen servant can’t make trained skillchecks and only works within 30/18.3 meters depending on edition; mage hand? You’re really trying to stretch the definition of spells to make a point aren’t ye? This isn’t mage the awakening, spells have well defined effects.
Ah yes, the alignment system, where mowing down tons of salients is okay because ‘evil’.