Hi F.M.Eletteromeccanica
You should be able to set the baudrate by using the PLUS+1 Service Tool.
Connect to the JS1000, find the baudrate parameter and change it, reboot the joystick, change the ST baudrate and you should be able t connect to the JS1000.
I'm not a CANopen expert so....
If you really need to use CANopen.
The JS1000 are using the CANopen standard so you should be able to find the information on the web on what message you need.
Let us know if you don't find anything, and I will try to find someone who might have the knowledge.
Have a nice day.