Because of your ability adjustments, these creatures are basically pigeonholed as casters. If that's what you want, more power to you, but if it istn't, then I'd suggest lessening the penalties and such to -2, and the int bonus to +2.

I'd change the wording on sixth sense just a little, to help with clarification.

Something like: "Sixith Sense: An Oriakia can sense little movements that other beings cannot, giving them a +2 dodge bonus to their AC and a +3 on Inititive checks." might be what you're looking for.