I have a Sim who has reached Level 9 in Magic Skills, but is an absolute failure at Summon Acquainted. It works maybe 1 time in 10. Is this part of the gameplay, or am I missing something? Also, should he need to review a spell every single time beforehand? If he doesn't he seems to only be able to do Fire and Ice. Seems an odd system.

(I have EPs: Late Night, and Supernatural, plus Midnight Hollow which is where this Sim lives)

I am assuming you are actually referring to the Spellbook from the Store, as witches don't actually have a Summon Acquainted spell on their own. If this is the case, the spells from the Spellbook are not connected with any skill levels you have as a witch. So yes, you DO need to periodically review the spells from the book to get them to work properly with any consistency.

If your spells from "normal" witch skill levels are failing a lot, check to see what wand you are using, as some have a higher chance to "fail" a spell. Or get the Magic Hands Lifetime Award, and dispense with wands (and spell failure) altogether.