It's just vague what's doing what until Venat tells us verbatim in Endwalker, not really retconning anything. Ifrit attributes our immunity to tempering to the Blessing, but everyone else says it's the Echo (likely because they don't know any better). Raises the question of how Resonance works, but.

The PC isn't actively controlling the Blessing, Echo, or flow of aether during the Lakshmi scene(s). They're just standing between the tempering blasts and letting it bounce off of them.

You're trying a bit too hard.