Sapph

Yomen has been confirmed as an Atium misting.

But that is normal feruchemical tapping. Since feruchemy is of Balance, it would have permanent phsysiological effects. But compounding is net-positive. STRONGLY net-positive. And - at least on Scadrial - constant use of net-positive investiture does cause physiological changes. So it is not out of line to speculate that compounding could result in savant-like conditions.