In Phase 1 of Ar Tonelico 2: Melody of Metafalicia when Croix's group is heading back to Pastalia after Cloche collapsed Cocona becomes targeted by Grand Bell Knights because she is infected with I.P.D.
To my understanding I.P.D can only be contracted by Reyvateil's yet no one bats an eye about Cocona being a Reyvateil rather her level of infection (thus the suprise deployment). both Luca and Cloche has had to have the Life Extending Agent administrated to them but Cocona has yet to receive one and while i've only just started Phase 3 there seem to be no indication Cocona is a Reyvateil (ie. she's not reading Hymmnos, not using Song Magic).
So is Cocona a Reyvateil? if so how far developed is she as a Reyvateil in comparison to Luca and Cloche