You are describing it as if the developer writing the regex/cron has no prior involvement with the app, project, or company and is brought on to transcribe a specification from English to code and nothing else. In that situation an AI-driven translator app makes a lot of sense, but that doesn't match reality.

The software developer has a lot of context with the app and project that cannot be easily passed into the translator (whether AI or human). Going from that state of knowledge to the code by an intermediate, compressed, lossy, ambiguous step of natural language is necessarily inefficient. Whether that translator is operating at human level or not is not the point, going through English is the problem.