You should read more of the actual books and not just rely on TTB memes, because "oh no, how could we have possibly lost to a phone company, what are we if we can't even do that" is not how the clans that did lose reacted in canon, and given two of those clans loathed the wolves, I don't think they were consoling themselves by pointing to the wolves managing to win. In canon, they started looking for a reason go break the truce and regain the momentum they'd lost shortly after the trial, and there's no reason they wouldn't do so here.
Given that in canon the schism wasn't caused by Focht only winning a major victory over the clans instead of a totally one sided one, and that 2nd star league fell apart for completely unrelated reasons, I don't see how any of that vsn happen.
They did no such thing. IS forces failed to follow clans rules of honor, but I don't recall them agreeing to a fight under clan rules and then flagrantly breaking them, at best they'd do tricks like Wolcott.
Yes, in the aftermath of a battle where the Warren's most skilled and canny advocate is killed, surely some other, even more skilled officer will emerge to keep the crusaders in check and prevent them from restarting the invasion like they did in canon. That sounds plausible.
The clans have consistently demonstrated that they don't need comstar's help to hold conquered worlds, and that they can expand into new territory and new planet's without ComStar.
Um, no, that's not how it works. Clanners aren't orks, they're not going to turn on each other because the boss is dead, they're going to follow the chain of command and hold together. It will impede them, yes, but it's notvlike the IS. An just shrug off the death of a bunch of thier upper command staff either.
Also, "just go for the ilKhans, lol" is easier said than done, given that ilKhans aren't soft targets by any means. The IS forces would have significant problems if the clans just killed a few of the successor lords, but you can't just run off and kill Victor Steiner-Davion anytime you want.