@bvdputte Regarding the name, you are sort of correct. It’s not a true relationship plugin, where selected pages updates automatically with a link back to current page (if I understand you correct). It’s not bi-directional.
But, in a sense, the name Relationship can be applied to this field. Why? Because you can select pages that belong to each other, related pages. And because the options are sortable, you can sort pages depending to how they relate to each other.
But I understand your question regarding if this is a true relationship field. A true relationship field should be bi-directional. In fact, for a large site I’m building, I have actually made a plugin that is bi-directional. It works like this: I have a field where I can select another page. The page I choose, will be automatically updated with a link back to the original page. If I later remove the link, the other page will automatically be updated with the back link removed. This plugin is kind of custom built for this specific site, but it should be doable to package it into a generic plugin for any site.
One of the future features I’m thinking to implement to this Relationship plugin is this bi-directional behavior. Time will tell if I succeed.
BTW: The plugin is inspired by this excellent field for Advanced Custom Fields (WordPress): https://www.advancedcustomfields.com/resources/relationship/