[ekiwi]

It seems like the real challenge would not be the translation of individual code snippets to a newer programming language, but more about adapting the code base to a different library eco-system. For example you would have to understand the exact behavior of the Cobol and Java standard libraries if you wanted to correctly translate code between the two languages.

You might also have implicit dependencies in the legacy code on the schema of some external database, all of which would need to be taken into account when migrating.

Also, tests might be missing, so how do you even know that your migration was successful?