That I2C reset issue, we also ran into it, but it was thankfully during development. Programming the MCU would of course reset it, and that sometimes happened during an I2C transaction.
Good call about those brownout loop.
One thing I started doing, working in a small company, is actually designing the pinouts myself. As a firmware engineer, I’m often much more familiar with the microcontrollers than the EE. I’ll of course discuss it, learn what are the directions a bus would go, but there’s a chance I’ll catch something the EE wouldn’t.
Also, re: debugger and logs. I’ve found that while a debugger is great for solving a bug, logs are preferable to find out where the bug happened in the first place.