Those so-called incantations Dean Bruce had been teaching were nothing more than famous quotes or sayings that he thought could be interpreted in a certain way. After all, his understanding and knowledge of magic were shallow—practically nonexistent.
The insights and power the system granted him were given as direct rewards and applied only to specific spells. It wasn't as though he had truly grasped the essence of magic.
As a result, while Dean Bruce could understand the literal meaning of the phrases, he couldn't connect them to the magical world.
It was only when someone he had bluffed successfully linked those words to this world's magic and comprehended a spell that he received the system's reward for understanding. Only then could he use that knowledge to teach others.
Since he hadn't yet earned that reward and had limited knowledge of magic, how could he truly guide someone else in its mysteries?