I’m sure there will be a ton of unexpected complexities that arise only when you are trying to push the limits, like in all engineering domains. And it’s all a highly interconnected system, you cannot expect to dramatically change the water flow without impacting others aspects.
I know it is quite distant, but from my experience in large-scale data engineering, 90% of the time goes in addressing subtle issues that can only be observed hours into a job, the rest of the issues are quickly resolved earlier. I am assuming that such complexities will be so much harder in physical systems, and even more so in biological systems.