I was under the impression that banks with core COBOL processes all had an intermediate layer in Java/C# to deal with these kind of integration.
We saw exactly the case of a new business unit being created, and like most other units it wouldn't get direct access to the lowest layer, and interact instead with a saner level of API and modules in the language of their stack.
Yeah that my impression too - I haven't worked in banking but I've worked at a few places with core functionality written in Fortran and then web-facing API layers on top of that (some was in Java in think).
We saw exactly the case of a new business unit being created, and like most other units it wouldn't get direct access to the lowest layer, and interact instead with a saner level of API and modules in the language of their stack.