Not sure if this could help, but you can have a try on creating a plugin to create element action and take a reference to the webpages below. And If you can find out a solution, please share to me.
I have figured out how to create a plugin with the action to add a new element (a button),
however I don’t know how to add a reusable element.
Because plugins use plain JavaScript and a Bubble Reusable Element cant be used with document.createElement.
Will I need to create my whole element as a Plugin? Or is there something I’m missing?
I think it is ok to build your whole element as a Plugin and here is webpage which is helpful for you to do that. You can comment in my forum post below and I can have a try on it if time allowed.