I haven't done deep research, but the research I made only said
"If you kill X ancient last, you have 50/50 chance to get either one of these Jewels".
I haven't got the biggest sample (12 runs, only Madawc last kill), so it could still be "luck" but :
When I kill in this order : Talic -> Korlic -> Madawc
I get Magic Jool
When I kill Korlic -> Talic -> Madawc
I get Lightning Jool.
Maybe this intel is already out there but so far from my research and what I've heard on recent streams, it seems like people are unaware,
So either I've had always "luck" and it was "just RNG playing out" that when I kill Talic first I get Magic,
But I doubt it.
very interesting observation, I know statues are not that readily available, but I would keep doing this for a couple of runs to see if you ever get it wrong. very very unironically, keep us posted!