I get that. My job is mostly writing Python scripts to keep an old Fortran based framework going, so I cringe when people get married into a language like this. I feel that all code should be adaptable and be able to absorb upgrades and changes. But I certainly understand. From my perspective if they were to rework my old Fortran code, it would take them at least a year or more to do it well. Most companies don’t want to spend that sort of effort.