The scalar field may become resonant with the grounding sheet, but the field should still exist between the two boxes.
The energy may flow through you and into the grounding sheet, but you will still have that energy flow through.
The only time the grounding sheet may cause issue is if it grounds enough energy to prevent you from tuning the system. However, if you are able to still tune and create the scalar field, then it is not a problem.
For more details, please check this link:
https://www.facebook.com/groups/spooky2scalar/posts/1075348023038755/
