I've found some pretty glaring issues with the rules.
One is challenges. The rules say the players should try to get models in a challenge into base contact but it isn't mandatory. It matters quite a bit though and there's no clarity. Does that allow us to move into an "illegal" spot? For instance, a champion moving to a corner makes him not centrally located as he must be. And if he can move to the corner but there's already a character (not in a challenge) in the corner he intends to move to, does he switch places with the character? And if so, what happens as soon as the challenge/combat is over? Do they switch back to their original, legal positions? Does my character get shunted to the back rank so the champion can go back to their position? They didn't even try to explain how this works.
But the worst rule is split profile. It's beyond busted right now. The essential problem is the way they describe split profiles as multiple models that make up one model. So if it's a chariot with 2 riders and 2 steeds then it is 5 models that make up 1 model. 5=1.
It is very clear that any special rule that applies to one of the models applies to all of the models that make up the model unless it's otherwise specified that it only applies to one of the models. Impact Hits is never specified to be "chariot only" on any chariot profile. So rules as written, a 5-part chariot with Impact Hits D3 does 5D3 impact hits because every model has that rule unless it says they don't. Now I don't think many people would try to pull that off in good faith, but there isn't a rules argument that they're wrong.
It makes the Anvil of Doom super weird too. If every individual model is also, the model, then technically the armor runes should apply to the Anvil and Runelord and Anvil guard. Are the armor runes being inscribed in the Runelord's armor? Yes. But can it also be said that the Anvil of Doom model has runic armor? Yes.
So T10 Anvil certainly seems legal, or adding wounds to both the Anvil and the unit, etc. It's all very weird.
There's actually a pretty simple solution to this mess, it just require errata in a lot of places. They need to make it clear that "models" consist of 1 or more "profiles" (not models). Most models have one profile, but those that have more than 1 are considered split profiles. Then specify in the rules whether it applies to models or profiles. Things like Impact Hits and Fly would apply to the model, but things like Furious Charge, Hatred, etc would generally apply to profiles (unless otherwise stated).
I played orcs yesterday and Tuskgor Charge (+1S), Choppa, and Hatred (Dwarves) for Night Goblins are not specified to apply to only one model part. So boar riders give choppas to the boars, the boars give tusks to the orc riders and ridden squigs hate dwarves. Is this intentional? Who knows?