Indeed that is the timing advancer also correctly called a centrifugal advance mechanism. The idea is that when the RPM is at idle, the engine requires the timing very slightly advanced (about 7-12 degrees) but as the RPM rises the engine is more efficient with the timing much much advanced. This advance is provided by the centrifugal advance mechanism located below the points plate. As the mechanism spins faster, the weights get thrown outwards against the spring tension, the central spindle turns in a opposite direction of the rotor movement to provide the required amount of spark advance. The thing you need to know about this device is that if for example if it is suppose to give a maximum advance if 18 degrees at say 2000 RPM, then no matter how high the RPM goes, the advancer has reached its limit and it will not go beyond the 18 degrees. So if your engine is misfiring at say 8000 RPM, the centrifugal advancer is not at fault.
This mechanism almost never goes wrong since it is so simple. At worst the weights jam up which can be freed up with a bit of lubrication. The springs can break or become weak. in both cases the advancer will cause the timing to go full advance at a lower RPM rather than the optimum design RPM point. In neither of these scenarios will the engine misfire. Your problem of missing at full throttle is NOT caused by a faulty advance mechanism for sure. I have worked on engines with a completely nonfunctional centrifugal advance and they still ran to full RPM without any misfire. The symptom of a jammed advancer is poor pickup and poor fuel economy. The symptom of broken or weak springs is knocking or pinging while accelerating at high throttle opening from low speeds.
You need to look at other causes of the misfire. Fuel starvation seems to come to mind. Is the carburetor the original one for the CD 200? Could it be that you have a CD 125 carb?
At this time I do not have any bike. However I used to ride a Triumph Tiger T100 in my twenties and thirties (sold years ago and replaced with a Mini 1275 GT). Now I am thinking of buying a BMW R100 but not having a place to park it is preventing me acquiring it plus the wife will not be too happy seeing me going about on it. So, for now I have no bike.
The electronic ignition I am using on my project is very different from what you need. Anyhow here is the link to the conversion I did. Though the design is different but the principal is the same. https://www.pakwheels.com/forums/d-i-y-projects/232265-1948-1-1-2-liter-jaguar-saloon-some-improvements-13. In post number 253 you will see the centrifugal advance mechanism of my project.