Manipulating objects script doesn't work

The script is this one. The drawn circle should be updated in relation to the two fiducials position but after is created it doesn’t update with a modification to the position of the fiducials. I added this line logging.debug(‘function executes’) to UpdateSphere definition and it never executes

You need to use the script repository examples that match the Slicer version. Your link points to 4.10 version and that works with Slicer-4.11. For the latest version, you need to use this link: https://www.slicer.org/wiki/Documentation/Nightly/ScriptRepository#Manipulating_objects_in_the_slice_viewer