At this moment I am searching documentations or trying to make documentations for the XML-Code which builds the script boxes in Choregraphe. For example, like you could see in the next images (1 and 2): what does „Input name="Multiplicand" type="2" type_size="1" nature="1" inner="0"“mean in the basic script boxes just like “Multiply.py”? It would mean one variable as input value in type number with "onEvent" in choregraphe graphic interface according to the image3, I guess.
It's very hard to find them on the official documentation website from Aldebaran or even by Google results. In principle I could already find it out with just trying to change the values and see the changes in choregraphe, but it's not very smart and takes a while. At this point, I’m really forward to hearing from you. That would be very helpful for the next students who want to understand more about choregraphe and who want to build choregraphe script boxes by themselves in Python code level.
Yes, that "Multiplicand" you see in the xml is the input you can edit via the gui.
You can create and edit Choregraphe boxes entirely through the GUI, editing their inputs, outputs and parameters; I recommend doing that instead of touching the XML; because the exact format used in the .xar file may change in future versions. I have used Choregraphe quite a bit and have never felt the need to directly edit the .xar (except maybe when resolving git conflicts, but that was years ago and since then we've been avoiding having to ever merge a .xar file).