So there is no such thing as an "existing design" ship unless you buy it as part of a flight of ships.
In the JSS case we bought the "existing design" for the Bonn (which is significantly different from the Berlin in a number of ways) and gave it to Vancouver Shipyards with the Statement of Requirements and they are modifying the design to fit that SOR. Bonn is similar to the Asterix for Germany, they don't have naval pers running the ship.
This means the design has a lot of changes from the original. First is that VSY when they want a subsystem put it out for tender. This means that whatever subsystem is selected is certainly not the same one that was on the Bonn. Same function, different design/contractor. HVAC, electrical, generators, navigation, RAS, all the systems suppliers, and subcontractors are different. Which of course means different designs to fit that stuff in.
The SOR necessitated different radars, OPS Room, the movement of the MCR to depths of the ship (on Bonn it's beside the Bridge... weird), new two new magazines, 6 OPS controlled weapon systems (4 NRWS and 2 CIWS), hangar and flight deck to fly and do 3rd line maint on the Cyclone (such as an LSO compartment), different comms, actual red processing (thus EMSEC which Bonn did not have in all but one space) and many other things.
The requirements are written as "performance" standards. This means the Gov't doesn't care what the solution is per se, just that it meets the performance standards. This allows the industry to come up with solutions. Which of course means the ship will be different than the Bonn. Technology has moved on, and other solutions for some problems are cheaper and/or better.
So when someone says "just build it like the Germans did" I kinda shake my head because you can't. There is literally no way to reproduce the exact thing. It's not how engineering contracting is done, and how requirements are met. Even if we paid Flensberger et al... (the original builders of Bonn) to build the ship for us it would be crazy different. Like how the Bonn is different from the Berlin. By using the German plans as a baseline we saved ourselves a lot of problems, but it's a baseline.
