Strikethrough Invalid Row in Relationship Tab

Attempting to create a client-side javascript method that can highlight / strike-through invalid Part AML relationship rows based on a relationship property (outdated date), when I click the tab.

I've been trying to replicate this github link:
Sample code to set the color of a relationship row based on property values. · GitHub

2 issues I'm running into:
1. I tried putting the method on a CommandBarSection Builder method like the post says and set location to: ItemView.RelationshipsCommandBar, but can't get the method to fire on tab load. ex. Pressing the AML tab on a Part Form doesn't run the method.
2. Tested whether the method functionality works by adding a button on the relationship command bar to run, but I get an error on the method .SetBGColor (error can't read property_D).

I'm trying to apply a strikethrough similar to the one in red-line view. I've looked through the forum and found some links to solutions for similar issues, but they were no longer available. Does anyone have any up-to-date links or solutions? Thanks.