How do I get better at complex, safety-critical control systems?

You can program most systems now. The complex, safety-critical ones, where a mistake hurts someone, still beat you. That fear is not weakness. It is the right response to work where the stakes are real, and it will keep you careful. Safety-critical work is a different discipline, not just a harder version of what you know. It is about imagining every way a thing can fail and building so it fails safe. That mindset is slow to grow because it comes from experience, review, and learning from other people's near-misses as much as your own. Find an engineer who does this work well and get into their reviews. Study failures in your field, the reports, the root causes. You build this judgment by absorbing how things went wrong before, so you can see it coming before it does.