Can staff use Gmail’s “Report Spam” button instead of the CyberNut Add-On?

No. Using Gmail’s “Report Spam” or “Report Phish” buttons bypasses CyberNut entirely.
When staff use Google’s buttons:

• The event is not tracked by CyberNut
• Users won’t earn Acorns (rewards)
• Training modules won’t trigger
• Real threats won’t appear on the CyberNut dashboard