Information: Under Binding iCloud 3.01 still the same. The Bridge need to be registered for every appleID of all family members to let ringing tone via ICloud work 
EDIT:
I ust looked the API-Documents from Apple. They had version Date of 2020-10-06 could be the point binding stopped working for ringing tones.
Don’t know the earlier version, but for ringing tone (Start_Sound) in the API there is a special Command for non owners (0x300) now different from owners Command (0x200).
So maybe the thing configuration needs a flag if owner device or not and a different usage of apples API