Specifically the database: If you’re not taking advantage of current technology I mean trigger programs, constraints & I/O servers, you’re building up technical debt and it’s going to cost you big time in the future.
The sooner you accept that a modern database will serve you better than using program centric techniques to do things that are handled by the operating system, the sooner you will realize the benefits.
The problem with enforcing data integrity in monolithic programs is it requires programming effort for something that can and should be done by the operating system.
One problem with keeping the business logic in a monolithic program is a file may be added to and maintained by multiple programs. Which creates a need to keep the business logic in sync in multiple programs. By consolidating the business logic in one place (trigger program/ service programs) you negate the need to do so in the application programs. It is simply the best place to do the job
Time for a new User Interface: It doesn’t matter what language you’re going to use for the new UI. If you’re not using trigger programs and constraints you will be forced to convert the referential integrity logic and the business logic to the new language. This means new programming skills will be needed and old programming skills will not.
You also need to consider what future demands are going to be put on your data, in the form of quality and security. I’m saying it’s better to deal with the database before the user interface. You may find yourself in a situation where you are forced to redo the user interface to meet your data requirements.
To see an example of a modern database using advanced RPGLE programming techniques you can download a savf with a small 5-file application from this open source page.