Hi Moto,
Edge guarding is not required on the VISO side as it is not effective on the VISO side.The ADM3053 board construction is shown in the table below:
Layer 5 is used as a stitching capacitor plane. Application Note AN-0971 describe the implementation of stitching capacitors and the use of Safety capacitors.
http://www.analog.com/static/imported-files/application_notes/AN-0971.pdf
Regards,
Hein