During the main story, Oliver gains lots of spells from various places and people. Some of them can't be used from the spells menu and in the Wizard's Companion they appear with dark background but without any special explanation why they can't be used.
Everything I found points that it's a lost cause and those spells can't be used, period. For example:
-
http://www.gamefaqs.com/ps3/998014-ni-no-kuni-wrath-of-the-white-witch/answers?qid=349186
The Quake spell cannot be used at all. As you might remember, it has been said that not all spells are meant to be used by all wizards (I believe it was Old Father Oak who said t hat), and quake (Along with a handful of other spells) is unfortunately one of those that Oliver, for one reason or another, cannot cast.
-
http://www.ps3trophies.org/forum/ni-no-kuni-wrath-white-witch/187336-spells-i-cant-use.html
There's just a bunch you can't use as far as I could tell. They did say early in the game that no wizard can use all spells, but then why even have them unlock in my opinion.
But I refuse to give up. Maybe if you finish the game 3 times or do something spectacular? Those spells are just too great to be just a tease! Any official information would be welcome.
Best Answer
No. You already have a couple of sources that verify this, you should just accept it.
Initially I was also confused about as to why they were there and how to use them, but it just isn't possible. I have come to terms with the fact that they are there to add extra content to the companion, and nothing more.