So I can't speak to whether a Sprite's Charisma is equal to its Attack, Logic equal to Data Processing, etc. (although that is how I would assume it is without rules stating otherwise). But I do want to voice a quick word on the part of that quoted statement about why the Sprite Powers are written using Skill + Attribute rather than just Level x2. It is because this way it leaves things open to allow other beings to use the powers also. At the very least, with the addition of Emergent Critters in Howling Shadows, I'm sure there is the possibility for a Critter to simply have a Power from the Sprite list, and they don't have skills set to a certain value. So having that write-up of what skills and attributes to use matters.
But yes, a clarification for Sprites on what their "Mental Attributes" are would probably be a good thing to have.