Ah, so it's intentional. Thanks for the info.
It's just that everyone was somewhat overestimating the forgetfulness aura of Sidereals and was preparing to have to let the characters forget all about our discoveries (we got past some nasty locks and traps to get a hold of Sid correspondence). But if passable resistance rolls are a sign of things working as intended, then we can use our discoveries more as a hook into getting more knowledge about the world we live in!
Well, just consider the consequences of it being that strong:
1. Sidereals are utterly unplayable in mixed groups, since most Resplendent Destinies are incompatible with Sidereal Charm use.
2. Sidereals don't need stealth charms - they just need to run away and let the enemy forget. Sidereals don't need to play smart to keep their involvement a secret - they can just run around anima flaring and murdering dudes safe in the knowledge that everyone will forget them. Sidereals don't need to play like spies, contravening one of the major aesthetics of the splat.
3. Non-Sidereals have no clue that invisible Fate ninjas are out to murder them, and will forget any murder attempts made. This is stupid, when Sidereals in the RAW already have an information advantage and the majority faction of them is positively incentivised to murder most other Celestials.
4. Being Outside of Fate is inherently basically mandatory for any non-Sidereal Celestial Exalt, as if you're Outside of Fate you ignore Arcane Fate. Infernals laugh and laugh and laugh at this.
Bluntly, if I could I'd make Arcane Fate weaker and make it rather instead blur their identity in the recollections. As I see it, Sidereals are meant to be Heaven's Men in Black [1] who scare gods just by their presence (the gods can
feel the presence of people with spirit-killers) before you even get into their influence, or the way that gods who seriously cross the Bureau of Destiny tend to... suffer demotions. Hence, for that all you really need is for people to remember the Sidereal as the fantasy equivalent of the faceless government agent. They remember they dealt with a mysterious person, and they also remember that there was something very (Maiden's Colour) about them. And so not really remember them as different people, which a) helps them do their job, b) makes it very hard for them to maintain a normal life, and c) means that at least some essence theorists speculate that there are in fact only five Sidereal Exaltations, one for each Maiden, but
they can be in lots of places at once.
So, you know. Basically I'm saying that Arcane Fate should practically speaking make people remember all Sidereals as if they were played by Hugo Weaving.
[1] Men in Yellow, Men in Blue, Men in Red, Men in Green, Men in Purple.