Can Humans transformed into Pirmals temper?

[Layte_Aeon]

...

A number of those points do have answers:

The Sahagin did naturally have the Echo. Anyone with a sundered soul has it, but it needs to be awakened, usually by witnessing a star shower or the like. And while theoretically generating the "resonant" is possible, from what we've seen, it's not easy, and comes with a few drawbacks. Not to mention, the Ascian's were never hinted to have such a power. Emet-Selch did note that they could raise a soul without the echo into an Ascian, but that it works better with those who do have the echo.

Zodiark & Hydaelyn are different to most other primals, in that there were the first ones and so made with different means. Zodiark was, in essence, a Mech-Suit for Elidibus, and so when he exited it as a new primal in his own right, Zodiark was left a husk of power. While Hydaelyn was likely the same, Venat felt no need to leave, and so didn't. Livingway mentions that Zodiark & Hydaelyn, due to the nature of their creation, didn't have tempering in mind, however Zodiark was so large and operated n so huge a scale that other beings would be affected by him. Much like how an engine will always make loud noises if it gets too big. When the Ascians gave the broken rituals to the beast tribes to conjure their gods, they did so in such a manner that summoning would maximise the impact, like making an engine designed to produce excess noise.

Also the Blessing of Light ain't tempering, Y'shtola can see tempering, and even mentioned the dangers of absorbing light in Shadowbringers. The Blessing of Light is, in truth, not one thing but a catch all term for any direct intervention by Hydaelyn. Stripping the primals from the Ultima Weapon, empowering the crystals of light, the aegis against aetherial corruption, a method of communion, all of these are manifestations of her blessing. And so all fall under the label, Blessing of Light.

[Cleretic]

Also the Blessing of Light ain't tempering, Y'shtola can see tempering, and even mentioned the dangers of absorbing light in Shadowbringers. The Blessing of Light is, in truth, not one thing but a catch all term for any direct intervention by Hydaelyn. Stripping the primals from the Ultima Weapon, empowering the crystals of light, the aegis against aetherial corruption, a method of communion, all of these are manifestations of her blessing. And so all fall under the label, Blessing of Light.

This is kinda true, but not quite right.

There is one specific thing that feels like it's codified as 'the Blessing of Light', and it's the 'traveler's ward' that protects against aetheric corruption. it is specifically a ward, it does this very specific thing, it has never been any form of tempering, and in fact the only person in-universe who ever suggests that it's tempering is immediately told that he's wrong by his own god, who's kind of an expert on the subject. (Weird how people only ever remember and put weight on one half of that exchange.)

Other acts by Hydaelyn aren't 'the Blessing of Light' and don't ever seen to be specifically called that in the game by my reckoning, but are understandably sort of rolled up into a similar ballpark by some. But if someone ever specifically refers to 'the Blessing of Light' as a specific, non-abstract thing, then it refers to the traveler's ward. Kind of a squares and rectangles thing.