Ilithad casting is intelligence based...saves are based on the type of attack (the nature of it).
I don't mean saves.
I'm talking about the [Authority] rolls and the Wisdom rolls to read minds.
Shouldn't all of those rolls be Int based?
If they were purely Illithid powers, then yes.
But those tadpoles have been tampered with and we don't know how much the Absolute (or who else) is involved. If divine beings/magic are involved in the tadpole creation, it would make perfect sense that their powers work with Wisdom rather than Intelligence.