(Posted updated, more in-depth version here https://forums.totalwar.com/discussion/294311/rune-of-wrath-ruin-seems-to-have-infinite-cast-range-when-cast-over-walls-edited-w-replay-info
Casting Rune of Wrath & Ruin way out of range:
It casts just fine:
Even works on the Warp Lightning Cannon way in the back:
(Link to the pictures on imgur in case hotlinking doesn't work for some reason: https://imgur.com/a/lFlXC0n
The bug works regardless of whether the rune is cast from Thorek or the normal Runesmith hero. I have not been able to test this on normal maps yet.