You keep bringing up one bad example (instead of all the good examples that can be found by googling it, which you claim to have done), and you're saying I'm sealioning?
Yeah, no.
(Also, sealioning is constantly harassing people for evidence... which is what you're doing by constantly demanding people defend the cook that they've already said is a poor example and provide you with more examples.)
No. Just when the PCs are there. The rest of the time, the entire house, for all practical purposes, ceases to exist. Unless you as the GM are actually keeping up-to-the-minute notes about it both before and after the PCs are done, of course.
If the PCs are only going to this house at 2AM and you're absolutely positive that the cook should be asleep at that time and not sleeping close enough to the kitchen door to hear, then they're asleep and won't hear the PCs should they fail. Then you pick a different consequence. I don't know how many times I have to say this.
Are you being particularly antagonistic, in the sense of doing things like putting out obstacles that are nearly impossible to beat, like they require a nat 20 or that the players memorize twenty different steps? No? Are you actually putting out obstacles that it's reasonable (not easy; reasonable) that the players can defeat? Then you're being neutral. Are you putting out obstacles that are both reasonable for the players to defeat and it will be really cool when it happens? Then you're being a fan of the players.
Sure, and this fails to address what you do if you're improvising--and in those cases, you've said you would, in fact, improvise. Which means that you may end up putting someone somewhere where you might not put them if you were thinking, or overthinking, about it during prep.
Which is exactly what fail forward is. Same concept, different names.
Incomplete information. Incomplete information plus a red herring.
As am I, and to get them I have read narrative games.
Y'know what? I'm done having this conversation. It started back up again because I was curious what fail forward would look like if there wasn't a cook and I shouldn't have bothered answering any of the other accusations or gotten back into the endless back and forth.