Your handset looks like an audio-based 2-wire BUS system (Linea BUS) with video hacked on to additional wires.
Maybe try configuring the Ring Intercom for a Videx 3176 which is a 2-wire audio-only handset?
Image from here.
Although the compatibility checker has this note, which may or may not be an issue:
Unfortunately we can’t see the recommended Ring Intercom wiring for the Videx 3176 in the online compatibility checker, which is frustrating.