So using tadpole powers becomes a problem only once narrator says so?

And if she never did? Besides who is the narrator anyway?

I'd say it's the inner voice (conscience) of the otherwise mute protagonist and therefore highly subjective.

Anyways I've said my part and just in case reiterate: please Larian no purity system for me (still waiting on explanation for the source od "Powers of purity" - I'm actually curious here)