I see that the wiki ScriptRepository might have some outdated examples as you are referring to.
https://www.slicer.org/wiki/Documentation/Nightly/ScriptRepository#Get_a_notification_if_a_markup_point_position_is_modified
@lassoan Do you mind updating these examples for the nightly documentation wiki pages?
Markups has changed a good bit in the Slicer nightly. I would suggest reading the markups section of the migration guide which details some changes about markup events. https://www.slicer.org/wiki/Documentation/Nightly/Developers/Tutorials/MigrationGuide/Slicer#Markups
Another discussion about recent changes to Markups events can be found at:
Handle Markups events from an external module