Don't engage, don't engage, don't... dang it, I failed my Will save!
So, if you ask me, in this scenario, I wouldn't say you're at fault for not forcing the issue; if anything, I'd say you're at fault for forcing the issue, by having all the Fey keep trying to pry the information out of the PCs. But I won't fault you for that, because you had multiple ideas you'd accept for the PCs goals of get the Fey on board, which sound fairly reasonable to my ears, and were trying to get the Players to make their own plan work.
What I might fault you for, though, is not spending the 30 seconds to 2 minutes with an OOC Sanity Check, the moment the Players mentioned their idea, if you didn't see how the PCs had a workable plan: "OK, so you want to meet with the Fey to get their aid, but how are you planning to get them to help?". That simple touching base whenever you're confused helps games run smoothly.
Alternately, I'd fault you for for not being confused by the Players' declared intentions of meeting with the Fey, if you didn't see how that wasn't something with a clear path to victory -> the Players likely misunderstood something.
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All that said, in the general case? The GM is the eyes and ears of the characters, they are the interface between the game world and the Players. There is IMO no responsibility they have greater than ensuring as seamless an interface as possible. And, at times, this includes making sure the Players remember or understand things that their Characters certainly would.
IMO, the "optimal" (internet word) implementation of that isn't to try to "railroad" (internet word) information into the Players, but to ask genuine questions, and, if the response shows an invalid game state exists in the Players' minds, then fix that game state, so you're both / all on the same page.
Clear as mud?
Saying "fire" is more urgent than "Pod People" is suss - you must be a Pod Person.
I've been using "fire" as an example for a bit now. The secret point of the fire was actually not an inherent property of its urgency (although perhaps could be derived from that), but that, in the case of a fire, it should be easier to see how a) someone could consider that "not their problem"; b) someone - especially but not exclusively a "not my problem" person - could care very much if the fire is likely to spread to, for example, the Fertilizer Factory (kaboom!) or to something they do care about. But even with that being easier to understand, the transition from "My home is on fire, please help!" to "Do you know where the fire is heading?" feels rather jarring, and not like something a Real Boy (TM) would say.
But, sure, we can use your example of a "reporting a terrorist cell". It brings in its own baggage, so I'll poke at that baggage, too.
If I'm reading a spy thriller in which a child tells an FBI agent (or a Police Officer) about a Terrorist Cell in their complex, and the 1st line out of their mouth is, "do you know what they're planning?"? I'll likely read it in a very patronizing voice, assuming the officer doesn't even believe that they're real / assuming that the child is playing a game, or has misunderstood something.
But fine. Let's say that the child brings the PO irrefutable evidence, like 2 quarts of nitroglycerin or something.
Eh, I have to build up to this, I have to explain where I'm coming from.
If I see a bank robbery in progress, and tell the nearest person I can find about it, and they say, "do you know what they're planning next?", my thought process will be, "they're in on it, they're trying to find out if they can afford to let me live".
In the specific example under discussion in this thread, the chain of events was "not my problem" followed by "do you know what they're planning?".
With me on the color pallet I'm looking at?
So, in this context, when I see a "neutral" telling of "a child plopped several liters of nitroglycerin down in front of the PO, requested help with the Terrorist Cell in their apt basement, and the PO asks, 'Do you know what they're planning' without first acknowledging that they'll help"? I have to step back from my color pallet enough to say, "OK, the PO could just be in shock that they survived the child bringing that much nitro into the police station, handling it so roughly, and surviving all the way here with that approach, that their mind is mush, and they just incredulously skipped over the social niceties and went straight to that step". Because, based on my experience talking with the fuzz, even they will at least hint that they're on your side before probing for information, especially if the person they're talking to is clearly leery or recalcitrant. In other words, even for your example, IME, this chain of events makes absolutely no sense.
Which was also part of the point of Superman, someone known to go punch evil in the face, without really planning things very well. It's not "trope", it's "roleplaying".
Now, it gets tricky what we're discussing at any one moment, whether it's the PoV of children who were expecting Superman, and how their reaction could make sense in that context, or me playing an RPG, or me IRL. But, yeah, there's very few situations where I'd expect social norms to allow a "do you know what the next step looks like?" query to go uncontested from someone who hasn't offered help, and the example of 'there's a fire' is one of the strongest contenders for that being an acceptable line of thought.