CPLEX doesn't support FORTRAN directly. However, FORTRAN can usually invoke functions in native libraries (DLLs, .so, etc). So some users used this feature to invoke CPLEX Callable Library (the C API). For further details, you need to check with the documentation or the community of your FORTRAN compiler.
Another way is to let your FORTRAN codes write a math model that CPLEX can read. Then invoke CPLEX interactive optimizer to solve the model and write out the information you need. Lastly, your FORTRAN codes parse the output and get the solution. (File formats CPLEX support https://www.ibm.com/docs/en/icos/20.1.0?topic=cplex-file-formats-supported-by)
If you still prefer submitting a wish, you can submit it to https://ibm-data-and-ai.ideas.ibm.com/?project=CPLEX
#DecisionOptimization#Support#SupportMigration