Manical as a typo for maniacal doesn't work in the sentence without a bit of a stretch of the imagination.

It's difficult imagining a person who is both maniacal and has a ludicrously solemn conceit.

I looked, too, wwh, for 'manical' and couldn't find it in any of my sources. Does the character description go on to show someone who is both maniacal and solemn?