Not really, sure they've gotten the occasional plot-convenient tidbit here and there but the Illusive man was running a relatively small organization prior to mass-recruiting indoctrinated thralls. They were good, but not STG good and not Shadowbroker good. Certainly not good enough to uncover something if the other two were trying to cover it up.
Cerberus had an operative inside an STG base on Sur'kesh I'd say they're just as good as the other two.
Maybe they kept Anderson out of the loop for that very reason. Maybe he disapproved and they told him they'd closed the book on it and the "Reapers" while they were really going forward.
Except he's part of the council so they'd have to share it with him otherwise they shouldn't bother agreeing with Shepard with having him on the council in the first place.
And I can't emphasize this enough, we're talking about something a hundred times less resource intensive than the Crucible's construction. The two aren't comparable.
Its still a large scale regardless, since the people building it will have to.......
1. Recruit the manpower to build the thing.
2. Get the resources to build it and the ships needed to collect and deliver them.
3. Have enough resources to set up a colony and defend it.
4. Make sure the thing can stay in FTL non-stop for a few centuries.
5. Have the means to repair anything that is damaged/fatigued during FTL.
6. Be able to deal with the static build up from constant FTL.
So its going to be very demanding in resources since there can be no room for error, its not going to be as small as you think it could be.
They lost a convenience, they weren't reliant on it. They've seen what Sovereign can do, it tore through the Citadel's defenses and would have destroyed the alliance fifth fleet too were it not for some weird feedback shock from Shepard destroying Saren.
The fleet was caught by surprise when sovereign attacked the citadel, if they knew sovereign was coming and prepared accordingly the situation may have been different.
I never meant to say s/he was, but s/he did make a stupid decision on principle, which describes not having a backup plan for fear of being "defeatist". I'm pretty sure the Ark was plan A, because they believed stopping the Reapers was extremely unlikely. Then Shepard brought forth the Crucible plans and they made it an act of last resort, which is why they would have made final preparations and launched after Thessia, the lowpoint of the war when all hope seems lost.
No the ark was never a plan A it would be just fleeing the galaxy because they can't be bothered trying to do anything to save it or prepare the galaxy for the arrival of the reapers. The crucible was plan A because it provided a means to defeat the reapers. By the time Thessia had fallen everyone one was already committed to the crucible and the war was nearing its climax not to mention Shepard got a lead on Horizon which would eventually lead them to the VI needed to find the catalyst. Not to mention if the asari shared the existence of the VI on their home world the war would've finished a lot faster and the ark wouldn't be needed.