I understand the rage that's coming for this book and the fluff/lore.
However, I really couldn't care less.
It makes perfect sense that Malekith, post-Finuval Plain, actually "gets it". He spent a century in the Warp fighting for his life, against N'Kari and many others. He saw and survived things which would have broken or killed most. He stopped being a caricatured villain and became something more complex. He still wants to rule, and he's possibly the only leader that Dark Elves would accept because he's so good at it. However, he's not just in it for revenge/the evulz any more, and he actually gives a damn about being a leader rather than just a ruler. He also has a legitimate claim to the Phoenix Throne and is sufficiently badass to save Ulthuan - because he'd prefer to rule than to destroy.
Teclis has always done what needed to be done, despite the misgivings of others. He can't afford to take a short-term view of things. He is ruled by his head, not his heart. That doesn't make him a bastard. It makes him the guy who does what he must, even if he is hated for it, because no-one else will, and because annihilation awaits his entire race if he chooses the easy path.
Tyrion... well, I've never liked that guy. To me, he always seemed like a Marty Stu of the highest order, the perfect exemplar of what I call the High Elf Ice Block Syndrome.* The Nagash book makes clear that he threatened the survival of the Asur because he wouldn't put duty before getting laid. He also tended to win through what felt like rather forced deus ex machina events - N'Kari's defeat at the Shrine of Asuryan and Poisonblade's defeat at Finuval Plain being the most glaring examples (the latter at least until 8th edition's Dark Elves book was released).
* = If the High Elves have an ice block**, and any other race has an ice block, the High Elves' ice block is colder, or otherwise better at being an ice block in whatever manner matters for the sake of the comparison.
** = "Ice block" is analogous for just about anything you'd care to mention, in the lore or in-game. Also known as blatant favouritism, but really only became a thing after Tuomas Pirinen's "updated" High Elves book several editions ago. For example, ithilmar was added, but conveniently allowed someone to out-distance Bretonnian heavy cavalry, back when heavy cavalry charges actually decided games. We couldn't have heavy cavalry that could charge further than High Elf cavalry, now could we?
"The wrath of a good man is not to be feared. They have too many rules."
"Good men don't need rules. Today is not a good time to find out why I have so many."