Choir and Twisted Domain levels

Hi there, (not sure I am posting in the right section by the way)

I am farming the unic Amulet Choir of the Storm in the Twisted Domain (difficulty I/II/III)

- I try to drop the best "lightning bolt level" : 20
- I saw in trade sections that it is possible to drop lvl 20 Choir with an ilvl 80 (meaning we can drop it in difficulty I)
- I only dropped level 17 and 18

Is there any way to obtain information/confirmation if Twisted Domain level has, or not, any consequence on the chance to :
- obtain lightning bolt level 20
- drop any Choir Amulet (we used to make stats showing that high Twisted domain allows to drop more types of items so reduces the chances to drop Choir)

In other words : is it worth running 1 time Twisted Domain III or 3 times Twisted Domain I in order to optimise the global chances to drop Choir lvl 20 ?

Thank you for any answer (I ran 30 runs in the Twisted domain and I cant say)

Bonus questions :

- Does Vall-orbing the amulet could change the level of Lightning Bolt ?

- What if I use Reforging Bench ? Does it reroll level of the Lightning Bolt ?

In the past I got a level 20 from reforging bench one time. the resulting item had an item level 84

I also downgraded 3x level 19 to level 18 in the reforging bench.

Not many samples but hope that helps, so both seems possible from my limited observation.