@Daoust, Eric Thank you for reaching out to us, As I see you are trying to investigate failed sign in attempts for the users in the federated environment ( ADFS).
Just wanted to check if you have got a chance to review this article which talks about securing AD FS against password attacks - https://learn.microsoft.com/en-us/windows-server/identity/ad-fs/technical-reference/ad-fs-password-protection#:~:text=of%20their%20account.-,Securing%20AD%20FS%20against%20password%20attacks,-But%20by%20taking
Let me know if you have any further questions.