The museum updated their website, so I was able to get some better insight into the original. I have not heard back from the exhibits curator, but have received a response from another of theirs, so hopefully will be able to answer some final questions I had.
Radschlosspistole (W2035) | Objektkatalog
The bad news is that the plans are completely wrong.
Confirmed issues:
1. The pan rotates to the side and the arm reaching to it is just a tensioning spring:
2. There is no wood stock. This feature can be seen in the above photo.
3. There is no side plate. Instead, there is a belt hook:
4. The trigger does not rotate a sear. Instead, it looks like it wedges a spring sear out of the wheel. Seen above.
5. The original has a second loop, so that they can work as a ramrod retainer.
6. The original gun is 12mm.
7. I am still trying to find clarification, but it looks like this gun has a metal shell on top of the actual barrel? It also looks like there is a separate barrel and plug, but the plug forms the core of the handgrip: