New XMP metadata Field in InDesign using Javascript

Looks like you already asked this and the recommendation was to create your own UI for that custom property of XMP. Since each of the properties to the left were added to the software, and their corresponding fields are formatted different, even if you could add a property like "Relay" with javascript, the file info window doesn't look for/support additional properties to be loaded and formatted.
https://community.adobe.com/t5/indesign-discussions/new-xmp-meta-data-field-in-indesign-through-javascript/td-p/12576528