I understand the question now.
The plugin was initially desgined for raw HTML, JS and CSS.
It was not aimed at designing a layout/content and creating a shortcode for the same.
Right now gutenberg has a feature called “reusable blocks” where you can group one or more blocks and make it as one which can be reused anywhere in the editor. This is kind of similar to shortcuts.
The other way is, after designing your layout/content in the gutenberg you can switch to HTML view and copy the HTML and paste it in Shortcoder which can be used anywhere. The same can be done to any visual editor available in the market. You can paste the HTML in HTML view to edit it visually again.
Anyways, I will still evaluate this requirement and the efforts needed. I’ve added this to my todo list. For now may be you can try my above suggestion as it still works as expected. Just that it is not seamless to edit back.
Cheers !
Thanks,
Aakash