I hope it’s a case of them insinuating her plan worked but it wasn’t actually the case and they reveal what actually happened in a flashback cuz if that maid actually managed to poison them I’m gonna throw a fucking fit for the exact reasons you stated
Let's hope is something like that, but is really annoying when they have this type of plot when the staff and the whole team didn't try their best or are smart enough. I love the ones when the plan is flawless and something goes bad, but you know the MCs aren't the ones to mess with. Like "The villainess turn the hourglass".
It bothers me so much how easy the maid got inside the kitchen, and how the duchess didn't warn the personal to no let this witch get inside the castle. Why the guards didn't prohibited their entrance. Why the staff and her don't treat all that group (except the brother) like what they're "UNWELCOME GUEST".