OK, trying to respond to a couple points brought up:
1) Oh & the squadron.
Jurati wakes up after the call to Clancy. But Raffi is calling Jurati a Romulan spy before the convo, and I think she knows about the tracker as well, and Picard knows Oh paid a visit. It is a leap, but not a huge one. Raffi would have made it... Picard?
2) Jurati 180
Maybe she feels that with Maddox out of the way, then more synths cannot be produced. Deed done. And that 1 synth is not that much of a threat. And she can just geek out about it. Especially since she is caught. Even if the repentence is not real, she has to appear repetent, it is her only play.
3) The Big Bad
They had to survive the event because they survived to engineer the 8 star system & leave the warning. So the synths did not wipe them out. If the synths were victorious, they'd remove the warning as well.
But if the big bad survived (unlike the Iconians and others floated), where are they now? They do not seem to be aware of, or mind, a whole planet of super advanced synths hanging out. For around 9 years at least. Is the danger passed?
Or, one could read the episode as saying that the folk who left the Admonition are NOT the big bad. They warned others. Do not do what we did to trigger the big bad. That interpretation would leave the Admonition Civ AND the big bad alive, at least 200,000 years ago. But BOTH seem not to be minding the planet of synths.
4) Zhat Vash & Data
I do not think they considered Data a real threat/above the threshold. He had no emotions. Did not eat or drink. Etc.