We know Zariel isn't redeemed because Karlach is running from her. I think you can even see her in hell through the vision you get when first meeting.
According to Niara, no module is supposed to disrupt the status quo either, but I'm not sure that applies as readily to computer game adaptations.
Niara knows her stuff.
The module had one of three endings:
1. party signs a contract with Zariel
2. party kills evil zariel
3. party, with the help of Lulu, redeems Zariel
Now the module has a pretty dark recommendation for the DM if the redemption attempts fails. Lulu, the cute comic relief companion, goes permanently insane. But in BG3 Zariel is both evil and alive. And we have a Holyphant in the game - perhaps Lulu has recovered from her insanity and is ready to try again? Could be fun.
On cannon - the current WotC policy is weird. It's essentially everything is cannon and nothing is. They've even been putting out conflicting cannon stories to underline this point. "Who is Asmodus? One rumor says . . . " (and, to complicate matters, Greenwood says that policy violates the legal agreement WotC signed with him. He states that the novels are still cannon)
