I think it's heavily implied that Hornet totally knew or at least suspected/ didn't ask too many questions cause she really needed it to work.
We're explicitly told that she personally helped to assemble the trap, plus she's usually 3 steps ahead of everyone in almost all other dialogue, & goes "As I thought" at every other reveal.
IMHO you'd be making her into a much boringer character if you postulate that she was actually 100% duped & never would have participated otherwise.
Plus if she had zero actual responsibility it basically turns the whole atonement arc into empty whining. (Both her & the Shamans did the best they could under the desperate circumstances they were in, but it's only realistic that the results are ugly, costly & unpredictable. Dethroning a tyrant is often messy & bloody!
The snails are all different in their degree of heroism & recklessness but Chapel Maid for example I'd say is straight up admirable hero trying to do something while many others were complacent with the status quo.)
She's being a bit hypocrital there / having a major Reaction Formation, for reasons that, however, make perfect sense once you see the flashback sequence. (in brief, she's trying to distance herself from having "fucked up just like her dad")
Likewise, Lace didn't "save Hornet", she doesn't even know Hornet's name, she did it 100% to spite GMS (as she clearly says), out of jealousy, because she doesn't want them to have their epic duel to the death/ family reunion without her. (Yes, it doesn't make a lot of sense to be jealous of being kidnapped & devoured if she doesn't play ball, but Lace is, like, fucked in the head because she was raised by a tyrannical control freak god-empress, & so attention/love/recognition-starved that even bad attention is preferable. It's not pretty or aspirational but it's realistic to how being starved of love can screw ppl up)
See the earlier scene where she tries to intimidate Hornet but fails at every step & then slinks off while GMS and Hornet threaten/posture each other. She laments that she's getting ignored in favor of the Weavers, Hornet doesn't take her seriously as an enemy either, she wants at the head honcho (& even when she shows sympathy on principle, Lace can't really process it as anything but pity/platitudes/condescension cause she's internalized that weak/fragile = worthless)
Interestingly this is reversed later in the 1st abyss scene where Hornet first adresses GMS but she has nothing to say for herself but to hiss in defiance, & it's Lace who shows up to gloat/ talk. She wants someone to hear her motive rant, ultimately her motivation is wanting to be seen & if she can't get it thru service & loyalty she'll get it through destruction & defiance.
Don't sand the rough edges of these characters, those are precisely what makes them so interesting & emotionally juicy
(That said, don't get me wrong, I love GMS but, like,... as a well-written, multidimensional complex *villain*. Erasing her villainly because of one sympathetic trait/moment is also kinda dumbing her down / not taking her seriously, when she's very much designed to be an evil counterpart/ dark mirror image to Hornet. I love that she feels like an actual person with a destructive pattern/entitlement more than a cartoon baddy... & that they pull that off while keeping her relatively montrous/remote/'godlike', but she's still a tyrannical ruler & toxic parent)
It's so rare to get female character with proper edges that are taken seriously. (& don't get any more 'punished' for morally grey/ unpleasant/ugly/messy traits than a dude would - GMS is a baddy ovsly, but Hornet can be an edgy pragmatic hero but still be a hero, & Lace gets to be that "tragic monster" style antagonist that's usually an angsty dude & you're supposed to feel sorry for her & want to save her even if she's not remotely a "good victim")
Don't declaw & sandpaper them please!