The problem with the Python transition is that the language is so flexible that it becomes challenging to understand if/where/when any code will be impacted by

The problem with the Python transition is that the language is so flexible that it becomes challenging to understand if/where/when any code will be impacted by a change. Unit testing becomes the static type checker (less so now that Python typing is spreading). For a statically compiled, AOT language, it should be easier to migrate the bulk of the code and identify the hairy bits. Which is not to say it would be easy or fast, but I think Python, Perl or other flexible languages are worst case examples for breaking language change migrations.