Side-Effects

A change in Spirit Root, Spirit Blood, or Spirit Essence usually meant a change in constitution or unique physique, but something like that...

'Unless it revealed itself, it was too hard to find and identify...' Davis mused.

For example, if Clara never displayed the peculiarity of her unique physique from the glow in her eyes, their parents would've never found out and connected it with the Transcendent Truth Eyes. It would've remained unknown until Clara investigated it by herself or by telling others she could see through the truth.

Davis also knew those who possessed a variation Spirit Root would usually have an innately mutated Revolving Core when they form their Revolving Core for the first time.

So, in the same way, if Tina Roxley's Spirit Essence had undergone a change, he wouldn't know unless it could show a peculiar feature that would allow him to differentiate.