Based on the avahi-browse output, you could try configuring /etc/sane.d/escl.conf, adding the following
type http
ip 192.168.178.5
port 80
If the scanner device is using DHCP, the IP address might change in the future. You could ensure that it doesn’t by reserving that address in your router for this device (based on its MAC adddress).
After applying the config to escl.conf, try running ‘simple-scan’ again.
FWIW, a similar recent thread discussing a Xerox device using the eSCL protocol: