How is Component > Customize inheritance intended to work?
Creating a Headline element with or without Parameters and setting the following:
Headline > Customize > Class = component-class
Headline > Customize > Element CSS = $el {color: #f00;}
Headline > Customize > Custom Attributes = data-component : component-value
Label Headline as My-Headline and Export Component checking Allow Customization.
On page use My-Headline Component and set the following:
My-Headline > Customize > Class = my-headline-class
My-Headline > Customize > Element CSS = $el {border: none;}
My-Headline > Customize > Custom Attributes = data-my-headline : my-headline-value
Save page and inspect on frontend.
The elements properties are only that the original Headline Component, none of the additional customizations to the My-Headline element on the page are applied.