The manual rearranges itself to create an entire chapter on the side effects of magical practice.

In essence: yes. But perhaps not the way he thinks. Working with the Speech will make him better at understanding things - anything and everything, from his own thoughts to quantum mechanics to the conversations between the stars. It won't speed up his brain any, but it'll give him a little more room to store things, because the vocabulary of the Speech takes up a lot of space and brings its own extensions.