Ok, a spirit gets an extra abilities for each three foce put into it.

A sprite has optional complex forms, but no way to get at them.
I assume each 3 ranks of rating gets it an additional complex form, but I've read the section three times, is this an error or am I just blind?

Is it safe to say if this eratta, or did someone find out where I rolled my glitch?

I've read it black on white, it's exactly as you say.

Types of Sprites
Sprites are sentient Matrix entities that come in several
different forms. Each sprite has the powers below as appropriate
to its type. A sprite has one optional power for every 3 full
rating points, chosen by the technomancer when the sprite is
compiled. All skills and complex forms are possessed at a rating
equal to the sprite’s rating.

I think it´s a typo. It´s extra complex forms you get to choose.