COBOL -> Misses the entire point of a legacy codebase. COBOL is not the problem.
The actual problem is the missing knowledge from the engineers the CEO downsized and sent their work overseas. This boils down to three things:
1) figuring out the call patterns
2) figuring out the architecture
3) figuring out the business logic
This is also why cowboy coders are dangerous in your organization, while having corporate standards and making your codebase self-consistent (aka "Clean Code") is the most valuable thing you can spend your time on.
source: I made a bunch of dollar bills working on Java / EIS COBOL systems that needed to interact at wire speed, while not paying Big Blue for their EIS Gateway Software.