I mean, in End Times they just ignored that entire throughline. Though also, when you actually look at their respective lives, that throughline doesn't really hold up. Like, Tyrion really doesn't care about who he hurts or even bringing Ulthuan into another civil war, and he is personally charismatic and martially gifted enough that he has been able to get away with a *lot* of stuff and build a following despite his supreme selfishness and reckless disregard - he can't really have been said to inherit all the good in Aenarion. Teclis basically has to constantly clean up after him to protect him (and the rest of Ulthuan) from the consequences of his actions - or at least to kick the can down the road a bit. And likewise, Malekith's early life (before he had millennia of people he trusted working to destroy him) showed a capable leader who cared for those he lead and who was able to forge connections with the Dwarves.
I do like the idea that Teclis was handed a plan by Lileath, and tried to twist it to fuck over fewer people, and it blew up in his face because some of his foundational assumptions were wrong, hence Tyrion ending up as the Avatar of Khaine and shacking up with Morathi, as he was the Dark King candidate and Teclis cleaned up after him and enabled him all his life rather than helping him to not be that.
Edit: that is, if he wanted to twist things to work out better, in my view of things, he would have tried to make Tyrion the Aqshy Incarnate after he became the Avatar of Khaine rather than doing the convoluted plan with killing Tyrion's daughter and then Tyrion and then shattering the heartgem of the Everqueen to bring him back, and not made Malekith an Incarnate at all but instead helped him to walk through the fires of Asuryan and become an actual Chosen of Asuryan, so that he could take off the armour and get some healing and learn to direct his anger at the people who fucked him over in the first place rather than taking his feelings out on the Druchii (who were basically his stress toys for the last thousands of years). And he would have left Nagash out and instead helped someone like Elspeth von Draken to be the Incarnate of Death, getting the support of however many Death Gods that hated Necromancy he could to fence Nagash out of the running. And he would have not made himself an Incarnate at all, he would have tried to keep himself as an anchor-point of Qhaysh. And he would have made one of the Dwarven Heroes the Hysh Incarnate (Hysh is the Wind of Stone and Purity, not just Light). Anyway, that is enough fixfic musing for one edit note.