I used to write tests for a cryptocurrency trading platform. I regularly talked to the auditors, as they were the ones who made sure that the crypto we transferred into external wallets made it back into internal wallets after the test.
I wouldn't say that I knew a bunch of accounting practices from talking to them, but I _did_ learn that the CTO and director of QA both lied to me during my interview. Sure, we made _some_ money from the spread as claimed in my interview, but in truth, the bulk of our money came from loaning our customer deposits to 3 Arrows Capital. I knew we were fucked _months_ before the company suddenly went under.
Yup. Engineers do have visibility into fintech systems that they implement, maybe even more so than the bean counters since they can trace exactly which txns went where. These things are logged.
I'm also not used to developers having that much visibility into accounting practices. And that seems like an odd way to structure things.