I was U.K. technical sales manager for an international switched mode power supply manufacturer who made power supplies for the the whole series of IBM PCs through to Amdahl and Cray supercomputers as well as for HP printers. I am familiar with power line harmonics and switched mode power supply line and EMC filters(EN61000 and FCC Part15)
Epson's R3000 should not be susceptible within a UK domestic application. My printer power comes directly from its own wall socket with no other connected electrical items in that room.
My R3000 is using only Wi-Fi for communication and my router occasionally requires rebooting but I would be surprised if this is resulting in the printer carrying out unnecessary purging.
I had hoped to find a forum for Epson printer users but have not identified any.