In the case of the coworker it seems like you could have documented each of these specific cases and confronted the person about it. How do you talk your way out of losing data repeatedly?
Some people can talk their way out of almost anything. I've personally had my mind changed about something that was totally obvious; it's a pretty bizarre experience, looking back. Sometimes it takes hours or days for the reality distortion field to wear off.
I've had at least one coworker like this at previous jobs. They've tended to fool me repeatedly until I notice the pattern and revise my opinion of them. The confidence they display makes me think they're smarter / more informed / more thoughtful than I am, until enough evidence causes me to stop all positive weighting of their opinions. It's worse when you have imposter syndrome for the first several months of any new situation.
I've had exactly one boss who understood (some) of what I do.
Managing others, I've been completely snowed by people who's work is outside of my areas of expertise (tech writing, translation, graphic design, etc).
We had a "hero" on one of my teams that was strong conceptually but made poor implementation choices. Hacks with poor design that invariably didn't integrate well. High energy, always jumped right in - when others wanted to slow down and consider stuff, it looked bad by comparison. Deadlines became more stressful with more last minute bugs (that he would special-case "fix" - hero!!), and it was impossible to complain about him because our manager wasn't deep into the code.
Your story is in past tense, have you since quit this job or is the manager and hero gone?
You needed code reviews and design documents. If your group was too busy for this, then it needed this "hero" to keep pushing code out the door instead of dwelling on design choices.