Consistency is dependent on the code base and not the "compiler" in this sense. If the code base has consistent patterns and only has one well documented way to implement something then the AI will follow those patterns, ie. If there is only one way to run a job, AI will use that method. There might be some variation in variable names, formatting, etc. but the core flow should be consistent between "runs"

You can and should still test your code , both manually and with automation to ensure it does what it says it does. Testing should be the way you are certain it always works as designed. IMO understanding your tests and test coverage is more important than understanding the implementation. This is why part of the spec for superpowers is a test plan, and that should be the most reviewed / iterated part.