Sure, there are several issues in the process (hence it is so difficult) the expert(s) must be actually expert (not that easy[1]) and the software house program

Sure, there are several issues in the process (hence it is so difficult) the expert(s) must be actually expert (not that easy[1]) and the software house programmer(s) and manager(s) need to be open-minded and willing not to take the (usual) shortcuts. [1] this is a pet peeve of mine, but at my age I can see the difference between seniority (common enough) and experience (quite rare).