Hi John,
Thank you for contacting Syncfusion support.
Currently we do not have support for Synchronized scrolling between two PDF Viewers. However, we have other events to notify the annotation add, edit, move, resized., also, pageChange event to notify the page change in PDF Viewer. Please find the below link to get more details about the PDF Viewer events,
Please try it and revert us whether the above events are helpful to achieve your requirement and if not please provide more details about your requirement and the use case scenario of Synchronized scrolling. It will be helpful for us to investigate further and assist you better.
Regards,
Akshaya